Is it a bad idea to separate two adult cats 10 years old that have been raised together since kittenhood?

Cats are creatures of habbit and these cats of yours obviously love being around each other (especially 10 yrs) I think its best to keep them together, they would probably miss each other and get very upset, and might even run away.

* Yes, this is indeed a bad idea due to the fact that cats are very sensitive creatures to change. The cat might end up becoming anxious and if you are to move them from different locations such as too another home the cat might be confused and end up running away in search of their usual home. The best thing to do in this case is to keep them together.