Baseball has been blessed with some great individual nicknames — the Splendid Splinter, the Colossus of Clout — and some great team nicknames, such as the Gashouse Gang and Murderers’ Row, but only a pair of standout hitting duos have been immortalized in alias.

The Bash Brothers, Oakland’s slugging twosome of the late-1980s, Mark McGwire and Jose Canseco, and the M&M Boys, legendary 1960s New York Yankees teammates Mickey Mantle and Roger Maris.

The Arizona softball team has them all rolled into one. Or, well, two.

Meet Katiyana Mauga and Mo Mercado, the Smash Sisters, the M&M Girls, the two new baddest hitters on the block.

They have been out of this world — or, at least, out of the ballpark — for Arizona over the last two months, lifting the 34-9 Wildcats to win after win. They had back-to-back home runs in a 7-2 win over Cal on Sunday, two days after Mauga went 3 for 5 with a home run, two doubles and three RBIs in a 15-5 win over the Bears. The weekend prior, both had their moments in a three-game sweep of Stanford at Hillenbrand Stadium — Mauga, with four home runs during the weekend, including a game-winning shot to defeat the Cardinal 5-3 on Sunday afternoon, and Mercado, with six hits and seven RBIs in the series.

The biggest moment(s)? How about twin grand slams to open the sweep and start the Stanford bleeding in an 18-12 rout.

“To stop and think about it is insane. I mean, it’s what we’ve always wanted to do, but to be successful this early and realize we still have three more years?” Mercado said. “It’s just that much longer of a ride, and we have to enjoy it each year, keep our heads up, stay strong, and if there are tough times, we know we have each other.”

That’s quite a bit of power for a pair of 18-year-old roommates who like to crank up the music for post-practice dance parties in their room, who crack themselves up with Snapchat videos, who have known each other since before they were teenagers and took unofficial visits to Arizona together, who have helped each other along in this, their first season in Tucson.

If they look relaxed at the plate it’s because they’re relaxed in the dugout and off the field, knowing that success comes with a sidecar.

With similar sluggers in Chelsea Goodacre and Kellie Fox, dual threats such as Kelsey Rodriguez and table-setters such as Hallie Wilson, it’s no wonder the Wildcats have outscored the next-best Pac-12 offense, Arizona State, by 34 runs, in one fewer game.

Arizona coach Mike Candrea expected production out of the youngsters, both the product of successful youth programs, but maybe not this much.

“With Mo and Kati, they both impressed me in many different ways, but a lot of it is their game maturity,” Candrea said. “They’ve been around this game. Nothing is going to faze them. They know what it takes to play this game at a high level. They both embrace the talents of each other, the mentality, the drive. When you have someone who knows where you’ve been, it can sometimes remind you.”

Still, the success of the newcomers has been astounding, mostly to each other.

“It’s been really important to both of us, seeing each other succeed,” Mercado said. “We’re all about the other person — when I see her hit a home run, it’s like: ‘Yeah! That’s my roommate! That’s my girl!’ ”

There has been a lot of reciprocated rooting this year.

Mauga is not just a candidate for Pac-12 Freshman of the Year honors, but Player of the Year. She boasts a .365 average to go along with 15 home runs (second in conference, behind Goodacre), 44 RBIs (third in conference, behind Goodacre and Fox) and 90 total bases (fourth in conference, behind Goodacre, Fox and Cal’s Cheyenne Cordes), all in just 98 at-bats in 38 starts. Mercado also has shined at the plate while starting all 43 games, batting .323 with nine home runs, 42 RBIs and 74 total bases.

Power is nothing new to the prodigious pair, and winning is nothing new to them, either — they were cornerstones on a Victory USA-Campbell squad that won the American Softball Association 2009 14-and-under national championship. There they are, five years ago, in two pictures on the team website — one, in dirt-covered softball pants, the other, in dresses.

Instantly, you’re reminded that their friendship goes further than the softball diamond.

Mauga says that Mercado is the more studious of the two, that she keeps her in check, makes her laugh, stays on top of her to-do list. She added that friends and teammates say they’ve been around each other too long, that they finish each other’s sentences. That’s not a bad thing.

“When I first got here, I was just so nervous,” Mercado said, elongating the “o” in “sooooooo.” “But having familiar faces when I got here — having someone like Kati who I’ve grown up with — they were there for me, and even when I still struggle, to have people like that help me definitely keeps me relaxed.”

They’ve thrived at the plate by surviving in a sometimes-messy room (mostly Mauga’s fault, Mercado insists and Mauga concedes), with enough of a pathway to “get by.”

In a small dormitory room, their belongings are separated, each with her side of the room.

Mercado’s wall is more vibrant, with pictures and posters, many of Arizona’s sports teams. Mauga’s side is almost barren, “just blank, besides like two letters.”

One is from one of Mauga’s little sisters, the other is from Mercado’s grandfather.

She’s never met the grandfather.

“When her grandpa sends her letters and notes, he sends me one, too,” Mauga said, beaming. “ ‘I can’t wait to finally meet you, keep Mo in check, watch over her.’ ”

Sounds like the message is being heard loud and clear, on both sides of the room, even above the blaring music, once this practice is over.