Hello, my problem is the following

I compiled one android project on two computers(computer1 - apk1, computer2 -apk2). So after i installed apk(1) on my smartphone, it was good installed. After i tried to install apk(2) on my smartphone, but i got error like "Application is not installed". So i couldn't install apk2. To install apk2 i have to delete apk1 and only then install apk2. To install apk1 i have to delete apk2 and only then install apk1. This is the same project compiled on different computers. So i don't know why there is the error. Please, what's is the problem ? i need a help.

and sorry for my english