It is possible to override one method from core mode by two module. I have two module that overrides send mail method and I can not combine these methods because each one does different another and is it a way to I keep methods?
If you want to modify same method by two module.
Then I am suggesting you to use
what you have to do is override one method in your one module and add cutom event code
Mage::dispatch in that method
and in second module use your custom event.
This is the best way to doing in this kind of problem
this post helps you to create custom event