I think your recorder detects what type of media it is (+RW or -RW) and creates the DVD structure differently. If my steps do not work on a +RW as it does on a -RW, it’s most probably the navigation is different.
Could you zip the original IFOs (VIDEO_TS.IFO, VTS_01_0.IFO) and the menu VOB (VIDEO_TS.VOB) from the +RW, and attach it here. I’ll take a look.
The extra 6 titles are quite common in some recorders. Actually they don’t take up any space, and the only difference is probably the navigation: one set of 6 titles is for Play All, another set of 6 titles is play one title and return to title menu like you want it to. But for some recorders, I find both sets perform the same function, it’s just that one set is not being used.