Try looking in the Settings menu of your Messenger app and see if there's any option that might possibly be related to that double text issue. You mentioned disabling it and then later enabling it again but all that does is turn the app off and then on again. If the problem you're experiencing is relative the app, that's actually still to be determined, the problem itself will still be there.
Go into your phone's Settings >> Apps menu, find and open that Messaging app, tap on the 'Force stop' and then open 'Storage' and tap on the 'Clear cache' button. (The app's cache is only for temp files and other incidental files, it does not store any of your saved data nor old text messages.) Something like a corrupt file stuck in the app's cache might be part of the problem so manually clearing its cache could help. Not likely in this instance but it doesn't affect anything to try.
And as you already referred to, you might want to try using a different messaging app. Most third-party apps will have a better feature set and be more configurable than the default, stock apps so you might find it worth switching over anyway.