I was using NB 3.5 and ran the installer for 3.5.1.  The 
only choice the installer gave me under "Import Settings 
from:" was "NetBeans IDE 3.3.x".  I don't understand why 
neither my 3.5 nor 3.4.1 settings were offered.  (I also 
had two even older versions installed, but I had renamed 
the directories for them).

As part of a separate bug I was researching, I uninstalled 
and reinstalled 3.5.1 twice.  I next uninstalled 3.5.1, and 
reinstalled 3.5 (after renaming the original 3.5 
directory).  So at this point I had 3.4.1 and 3.5.  I 
installed 3.5.1 again and lo and behold, both 3.3.x and 3.5 
were offered as "Import Settings from" choices.

I would think any install of 3.5.1 over 3.5 (or perhaps 
even 3.4.x) would show this.

Because I had a 3.4.1 available, I expected it to show up 
for "Import Settings from".  I also expected 3.5 to show 
up, but it only did after a "fresh" install.