I agree with kung fu lola; these things have a way of working themselves out. Usually the child comes up with a naming system that is more meaningful to them that anything that the parents might have chosen. The nicknames we give our loved ones are too special to be mandated by others.
Plus, I think the French mere is too close to merde, which basically means “Oh Shit!”
CJ
You could use the name I use for my mother:
Mimi.
What makes you think the parents pick what the kid calls them?
Whichever takes care of her and watchs her most will be Mama/Mommy. The other will be something else. The linguistic theory is that the “Ma” sound (it’s Meh in Thai, BTW) is instinctive and is said when you need comforting or are “hurt” as an infant. Whoever heals the hurt is mother. Maybe said a better way, whatever sound you react to will be the sound that they call you.
It’s only as they get older and speak that they start to really use names. And I don’t think it’s confusing to the kid to call them both Mommy. The kid will know the difference. How about Mama A and Mama B, with the first name as a differentiator?
YOT!
As in “You Over There” 
That is correct, but as far as common toung:
Arabic: Mama
French: Maman
Polish: Mama*
*an addition. The proper term for mother in Polish is: Matka
Um, I’d like to know where you got this. Italian words for mother are usually:
Madre (proper)
Mamma (informal)
We use Mama for my SOs mom and Mama Niki for me.
Of course, that’s us speaking to the dog…
“Are we going to see Mama?”
as opposed to
“Mama Niki’s gonna feed you now!”
If I call my self mama, she runs to the door to go to mama’s house.
So I would recommend Mama Lisa and Mama Rachel. Though, if you have a name that sounds a bit like Mama (think Mama Monica… which is a bit of a mouthful) Mom and Mama are nice.
Friends of mine had this problem. Only they aren’t the mothers, they’re grandmothers. They didn’t really know what to do, but the baby fixed it himself when he began to talk.
What do you call your lesbian step-grandmother?
Ta-Ta. Now all the kids growing up in the extended family call her that, even the 18 yr. old nieces and nephews.
What I’m saying is that most kids come up with their own names. My nephew insists on calling my father Papa. Nobody in the family has ever used that name, we don’t know where he got it from. He calls his other grandfather “grandpa”, but not my dad, he’s Papa.
…and this thread was bumped from oblivion because… two banned posters are on it? To further someone’s agenda? What? 
Suki (or Suekey? not sure of the spelling as I’ve only heard it pronounced, never seen it written), It’s a term of endearment my FIL used instead of mom, mommy, momma, or whatever for his mother.
Cecil
“NoCoolUserName” works for me.
The GrizzCub used to call GrizzWife “ma-my”
emphasis on second syllable.
Pronunciation…
‘ma’ is pronounced as it is spelled (rhymes with fa la la la la)
‘my’ is pronounced as it is spelled (rhymes with bye)