That's interesting Red Spot. I had not thought to try that as every other file seems to complain at double entries.

Has it been tested thoroughly? What happens if you have building conditionals testing for the existence of that building? Which one does it take? How does it affect scripting when testing for a building in both those trees? Do the associated text files work correctly for both? How does it display in the building browser? Presumably the cards all work? Does the second entry count as another entry or can it be used to deceive the engine into having more than 64 tech trees? What happens if the tree name is the same but the level names differ? The EB file also accepts double entries then?

Lots of questions.

I'll update the EDB if this can be shown to be working smoothly and of use.