Install conflicts possible?

I have never installed Openhab before but wanted to give it a try.

I have a LAMP server running MariaDB, any reason I should setup openhab on separate hardware?

Depends on the hardware. If you have all that on a first generation raspberry pi, you probably should put OH on another machine. Otherwise, so long as nothing is running on ports 8080 and 8447 you should be fine. If you do have something on those ports you can configure OH to use alternates.

Ok thanks, I should have said its running on PC hardware so plenty of processing power.