Help with Summer Exam Sheet!

I don't understand my Summer Exam sheet which lists all the exams I'll have. There seems to be duplicates, but I don't know. For instance:

EDEXL/GCE GCE/B 6HI01D History 1 Option D
EDEXL/GCE GCE/B 6HI02C History 2 Option C
EDEXL/GCE GCE/ASB 8HI01 History

Why is there three exams? I'm resitting Unit 1 and doing Unit 2, what is the other one?

Then why does it list an English Language Unit (LG1) which is coursework, then do a separate one which is named "English Language AS Cash-in" surely that is the exact same thing?!