First item looks like a strap juction, could date back to the Iron age, second is a Medieval Buckle with small integral plate..13th-15thc...two nice finds, and Welcome to Treasure Net
I think the first is missing a rectangular loop, not seem this arrangement on a belt slide, but it fits the general features. The loop which I haven't seen on this could easily act as a suspension loop. I agree with SS that it's most likely 1st C AD & Roman (as I found a similar shape belt mount, which I IDed).