Due to the very bad distribution ratio this time, and the fact that I need to purchase at a site with the new checkout, I've made good use of the multi-tabbing function and gotten a few purchases with a single code.
I have a 65% code which I plan to use for two or three new releases next week (I sincerely hope the codes still work by then).
GM, you may try multi-tab if both the books you want are available by the time you get a decent code.