Both boards have 2 physical X16 slot but with one running on X4 speed. That limits them to Crossfire since SLI will not work on X4 speed. Neither is though recommended for dual cards, it would be better to get a board that can do X8 X8 with dual cards.
Budget builds really should be based around single cards (one powerful better than two weak) and that is what those boards are marketed for.
Yes I suppose you're right. My friend was encouraging me to find one that's x8 x8 so I can use dual graphics, but I figured I could be just happy with a single card. And, of course, his build costs over $1000.