Well it worked for me, playing it with PowerDVD. Did you check the Destination directory for IFOs same as source? And did you start with 2 directories with only the required vobs in each.
However there is another way that might work. Run Ifoedit, open the vts_01_0.ifo file (i assume that'll be present)..
Select VOB Extras & check the split to 2 DVD-Rs & take it from there. You'll need to select directory 1 & directory 2 etc.
I should emphasise that I've never done this , I'm only guessing.