The IC2 and TechReborn blocks and items are still duplicated.

Is there an issue with this, as long as its not stopping you from playing with either mod its fine in my eyes.

Of course it doesn't prevent to play, but it creates duplication and confusion, and it uses a lot of ids for nothing, and ids aren't unlimited. (that it's the modpack dev who speak :p)
Anyway it's not really a normal behaviour for a mod which is supposed to be an IC2 addon and GregTech resurrection.

It's what I had proposed in first time, an option for disbling the duplicated blocks when IC2 is present. ;)

it's not really an addon though when it works completely fine without ic2 installed, it has it's own power system and set of machines, that being said there should be a config option to disable the "duplicate" blocks.

Uhhh, this may get fixed at some point, but I think the best way to play is either with TR or with IC2, pick your favorite.