ID for Off-Brand 1x1 Round Plate, Stud on BOTH Sides (1 is Hollow)
I don't know this exact brand, but please note that Mega Bloks (now Mega Construx) has those male/male studs. They appear in many of their sets and come in many different colors. They are exactly one plate tall, just like the one you have on your picture. The Mega version has a hole going through the middle to accommodate any bar shaped piece, which makes them even more useful!