Double WordPress plugin

Hi,

Newbie here with wordpress, so please pardon me with the noobish terms and words used.

Firstly, I’ve installed a double wordpress plugin into my domain and my subdomain..

let’s say I’ve installed one into example.com and the other in example.com/second

Now I’m facing the issue of having to login separately into both accounts but they are the same domain.

The reason for installing a double plugin cause I wanted to run a certain program which was necessary to do that. Or I should say by doing that it solves the issue of able to run the program.

My Questions is. Can I like merge them now?/ How do I merge them? Cause I’m getting way confused with handling php for 2 sites…. or 1 sites with 2 plugins..