Only one and even after unchecked from the manage plugins page still executing, if I check the both I get duplicated custom gl lines.

is the GL plug-in set to run synchronously or asynchronously? Because a few years back we ran into a very similar scenario, and it was a bug related to asynchronous GL execution (edited) you might need to reach out to support. We found out, from support, that the GL plug-in pages themselves are kind of buggy. For one thing, they only work correctly for Classic Center roles, regardless of permissions. Because of that, there are three GL plug-in implementations I created, yet I can’t even see them myself, but they are they are there. And I do have the correct permissions to view and edit them. Additionally, if you are able to, try and change the plugin execution to synchronous and see if that changes the behavior. If so, the async bug might be back again. It was supposedly fixed several releases ago. I do know a change was made with the timing of when asynchronous GL plugins start running fairly recently (I think in March). It was a fix made outside of the major releases.

Thanks.