Ruth, It seems no one else is online right now, so I will try to answer your questions. I asked these same questions a while back, and I will try to recall what Ione said.
There are several varieties of Marans. There are Black Copper (Black Copper/Blue Copper/Splash Copper), Wheaten, Black (which is Blue/Black/Splash with NO copper), Birchen, White, Cuckoo,etc .... Each variety should be bred only within their own variety, (unless for some kind of a project).
So, yes, you can put the blue copper together with black copper (and with splash copper).
Breed wheaten only to wheaten. Breed Black (B/B/S) only to Black. Breed Cuckoo only to Cuckoo, etc.
A Wheaten Marans roo looks just like a Black Copper except for that wing triangle, I believe.
These are the different combinations when breeding Blue, Black, and Splash (BBS) birds:
Blue x Blue = 25% black, 50% blue, 25% splash
Blue x Black = 50% black, 50% blue
Blue x Splash = 50% blue, 50% splash
Splash x Black = 100% blue
Black x Black = 100% black
Splash x Splash = 100% splash
Hope this helps.