Is there any order in which elxr linker links the project files?

I am using MULTI IDE and elxr linker. In my project i have included a library and 3 tasks running in 3 different VAS. If i change any library file and build the complete project (not re-build) the changed file is getting compiled and linked to one task. And without any change if I again build the complete project (not re-build) the other 2 tasks are getting linked for the file changed in the library. Can someone explain why this happens?
Thanks in advance