Maybe one of them is for older/past version of Firefox. The best way to go to current version of Firefox profile is to:

• go to Address Bar, type about:support
• click on Show Folder/Open Containing Folder

it will go to your current version of Firefox profile

You can look at the file dates of the files in both profiles to see when they were last used.
You can check in the compatibility.ini file which Firefox version last used a profile.

If you want to start over and unify your profile. Delete the existing ones and create new one. You can do this by copy pasting this " firefox --profilemanager " into the run command (Win+R) and enter. Delete the profiles in the manager and create a new one.

Rakshith, that will delete all his personal information, probably not the best solution.

Thanks for pointing that out , I think when I mentioned "Delete" , I meant the user's data would be lost unless another copy exists.

i remember quite a while back i had Firefox issues and went into my profile and made some adjustments. i really didn't know what i was doing. anyhow, now i have the two profiles. the smaller of the two appears to be the latest profile.

isn't there a way to just combine the two and then end up with an updated profile? i thank you all for your answers.

It depends on the uncommon data you have b/w the profiles. If its bookmarks then you can export as .htm in the bookmarks manager and import it in your preferred profile. How about the Firefox sync? Create a sync profile and sync everything then to move them to another by switching the profile and entering your sync account details into it and it will come back.

my thanks to all of you for your help. i now have enough info to proceed.