Crib Problem

The girls are now 81/2 months. They are so cute. I keep debating if its time to put them in separate cribs

The sleep well together most of the night. They can also cry all they want and the other doesn't wake up. But they are now in the crawling phase and if one wakes up, she'll start crawling all over her sister waking her up and then I have two awake babies. Those of you out there who have twins- at what point did you make them sleep in different beds?
This last week we were at my parents. I put them in different play pens, each play pen seemed a little small to put both babies in. Every time they slept apart was miserable! By morning I was in the bed with two babies. I finally gave in and put them in the same bed and it was so much better. So which is the lesser of the two bads?- Having babies wake each other up by crawling on the other, OR having them not sleep well because they are by themselves? 
The other crib problem I've been having, is more of a bed time problem. Every night there is one baby who goes to bed with complete ease, while the other baby refuses to go to sleep and I have I can't get them to go to sleep for the life of me. Then eventually the awake baby will crash and I can put them into bed. Its not always the same baby. Its the same thing every night. 
How to solve this problems?