I had a whole house preview name WH 11-6-14, but I need to tweak it so I created a new one and gave it the same exact name. No error message that the name already existed was displayed nor did it ask if I wanted to replace the existing model. When I looked at RGB_effects.xml in notepad++ I saw that two models with the same name had been created. I manually deleted the first one. I used the same name hoping that when I went back to tweak sequences that had already been created that NC would use the modified model. btw, that did not happen, instead the xseq opened with the original model column showing, but I could not change anything. I went back to display elements and added the second copy, then copied all effects from column 1 to column 2 and then went back to display elements and then could modify my effects and resave the sequence.
I know NC is in a state of flux and time crunch but thought this info needed to be passed on to the developers. At this stage I am not considering it a bug, just something that has been gotten around to yet. I appreciate all the work the developers have done, they are helping me put on one heck of a different show this year from the past 7 years.
