Two Gamertags shown, Old one shows in games???

If the gamertag was changed now, try waiting a little longer until it syncs.

But anyway, your old gamertag is shown in the same games, and your new gamertag appears in some games along with your old gamertag in your profile

Could two system linked consoles, show two gamertags on the one console etc..?? Seeing how the two gamertags, are playing different games at once...

My son changed his gamertag about a month or so ago. His new GT was shown immediately on his dashboard etc, but still displayed his old GT in games. After several days, it resolved itself and showed his correct(new) GT.

Xbox is currently in transition to the new Gamertag system. Since this transition is not completed, you can get results like you see that you see two gamertags on your screen.

This will be fixed sometime after 2020 started.

Until then it's just a cosmetic issue, where both your old and new gamertag are shown. The first change seems to have happened on a system that didn't have the new Gamertag system in place yet, then Xbox rolled the new Gamertag system out to your area, and
when you changed it back, the change was made with the new Gamertag system, resulting in the display of those two gamertags.

You'll just have to be patient and wait a few more months until all systems and apps have been updated to work with the new Gamertag system.

In the mean time, the "old" gamertag is used with most games and systems that still mostly access the old Gamertag system.

Nope still got my old gamertag on there and I did pay for this one tho when I click "Choose your new gamertag" it shows my new one but when I back out it still shows my old gamertag.