I thought you were connecting two F8 instead of a single F14...
Connecting 1 for one means you are forcing the ballast to operate nelow its rated minimum arc voltage, there the current may become higher...
did you look up the upload? look at the ballast being used (in both this thread and the upload on the gallery)
its a series burning ballast
its rated for 1 F14T5 to 2 F35T5
2xF8T5 is (just slightly) more than 1xF14T5 so its not going to be a problem in that regard...