My original post was before the forum crash. Probably 2 years ago at Sam's Club they had two types of tri-chlor pucks. Both same weight, same concentration, same listed ingredients. No mention of copper. I know that because I was aware of the copper addition at the time so I specifically looked at the label. One bucket $10 more than the other. The more expensive was tagged as 'all purpose' or something like that. Nothing more to say than just try and be aware.
Al