Yes. Cheaper weights generally will pretty big swings on the larger plates, sometimes as much as 5lbs wither way. It isn't so bad with smaller plates as you can cast them pretty cheaply and accurately. A lot of the Chinese companies don't replace the molds when they get worn, use poor quality iron, leave casting flaws, etc.... on many plates, especially the large ones.
It was a big deal at many of the 60's-80's power meets as you'd a record attempt would weigh light or rediculously heavy sometimes as much as 20-30lbs. If you look ot pics from that time, you'll actually see the real weight inked on the sides of the various plates. Perhaps if the gym will allow it, you could weigh out your plates also.
Mis-loading one side of a bar by 5-10lbs is a recipe for all sorts of problems like tears, etc... too. So watch those plates.
Iron Grip, Ivanko gray class or better plates, and York machined plates with the milling swirls on the back are all pretty accurate common gym plates, usually only off 1/2-1lb at best, most times.
Also, if your university or gym has quality bumper plates handy, use those. They are the most accurate plates you'll find in most gyms.
