Tried placing an order for an expo gas block, and adding discount mid gas tube. 15.95 gas block, 8.95 gas tube(7.95 doing combo price).
That was fine.
Added another expo gas block(same one), this time with a carbine tube(8.95, but 7.95 combo price).
After adding the second combo, my cart showed the two gas blocks, 15.95 each, quantity 2, total 31.90.
Then showed carbine tube, 7.95, quantity 1, total price 15.90
And mid tube 7.95, quantity 1, total price 15.90.
I ended up placing order with one combo, then adding other two items individually, as every time I tried doing two combos, it doubled the price of each discounted add-on combo item.
Turned out that carbine tube was on sale for 7.99 anyways so after the save12 discount, I was only 3 cents off what the combo price would have been.