Is it alright to mix different brown leather pieces in ur family room

IMHO, it's your family room and you should decorate it the way you like. I think mix-and-match is fine. Add a few pretty pillows or other items that share some of the same colors and go!

As long as you like it, do as you please!

If you like it that way...it is a great idea.

I don't see why not. How many different brown pieces do you have in the room? If you feel there is too much brown in the room (brown leather and perhaps, brown wooden tables, etc.), you can always introduce cream colors (for example) in a throw, cushions, decorative bowl or vases, etc. to lighten the look of the room.

Absolutely, what I like to do with mismatched furniture is to use the rest of the room's decor to tie it all together- like with a gallery wall using frames with all the colors, ect

Definitely! Have fun with accessories. When I want a new look a can of spray paint does the trick, coordinating picture frames, lamp bases, vases, etc.

The days of matchy matchy furniture sets is largely obsolete unless you are just starting out. It's costly to buy a set of furniture when you need one piece. As others have said, pillows throws, etc. can make a room more vibrant and tie things together.