Duplicate Planes in v3 and v4

[planenut 19]

Some while back when Carenado/Alabeo started upgrading their planes for use in P3Dv4 I naturally did the upgrades.  I started getting messages saying something to the effect (can't remember the exact wording) that I had duplicate planes with the same name.  So before I upgraded each plane to v4 I would delete the v3 version.  Seemed to work ok as I no longer got the "duplicate" message.  What I have recently noticed is that the planes I thought I had deleted were still installed in v3 even though they were no longer listed under Sim Objects/Airplanes.  So to investigate further I went to Windows/Control Panel/Programs and Features and deleted a particular plane.  Sure enough it was gone from both v3 and v4.  Redownloaded and reinstalled into v4 only and sure enough it showed up in both versions again, although still not listed in v3 under Sim Objects/Airplanes.

This is not really causing me any problems - just trying to figure out why the planes are being installed in both v3 and v4 when I only select to install in v4.  I don't fly these particular planes in v3 any further - only in v4. Anybody else experience this or have an explanation?  Thanks.

Jim