I need to replace the twin plastic tracks (see pic below) guiding the tops of two sliding mesh screen doors attached to the back entrance of my house. The tracks are plastic and come in one piece, but one track (green arrow) is slightly (~0.5in) higher than the other (blue arrow). The higher track is breaking apart (red arrow) causing the door sliding on that track to dislocate when sliding. The replacement looks easy if I can buy this type of twin tracks somewhere, but I haven't been able to find it online, maybe because I don't know the right keywords to search for. Does anyone know the name of this type of twin tracks?
Sliding screen door "tracks" are not some generic part that you can replace willy-nilly. They are a part of the entire sliding glass door frame assembly. Unless you can find the original manufacturer of your door unit (unlikely) and get just a part of the frame assembly (very unlikely) then you wont be able to replace that.
The replacement looks easy
Even if you could buy the OEM upper frame piece (very unlikely), replacement would involve very intrusive work including removal of all glass doors and panels and separation of the frame from the plaster/stucco/trim etc.
You need to pursue a repair path, which can be complex in its own right. IMO repairing your existing track is your only option.