There are quite a few people who have taken EFT and re-labelled it with their own name. Some because they are full of ego and want to pretend it's their own technique, others genuinely because they have taken EFT and incorporated it with other techniques or practices to create something new that they find works.
I hadn't heard of GTT before (except in my job as a software developer where GTT means Global Temporary Table).
There are loads of EFT books out there, and I have a few, but generally they are people just supplying "add-ons" that they have found beneficial, but I know area already covered by other techniques. It would be interesting to know what the GTT technique is, but not so much that I'm going to buy another book on EFT.
Hugs
Giles