Most pet shops I've been in can't tell the difference between a ribbon snake and a garter and since ribbons will eat crickets they think garters will too. If they are feeding them crickets it is unlikely that they will know what species are they.

Try washing the pinkies first and then rubbing them with a fish to "scent" them. They will smell more like what they know is food and hopefully be more willing to take them. Eventually, they ought to take them without scenting them first. Garters will also eat nightcrawlers (never use red worms or what they call wigglers - they are toxic) and raw cut up fish like trout.

I agree that they both look to be male, a female will seem to suddenly "pinch" in just after the vent and have a shorter tail than a male who will slowly taper in after the vent area. It also looks like two difference kinds of garter, you can tell the red-sided and I think that Bay Area is right about the second being a elegans terrestris though I'm not going to swear to it. Both are beautiful snakes, congrats.