Czechoslovakian 9mm 1949-51

Recently picked up couple of '40" round boxes of the subject ammunition. labels are mostly gone. two boxes are packed in 8 round strip clips for SMG and other is loose (and more than 40 rounds.) what was interesting is that one box had a lot of red seal on the bases. (Note these are apparently repacked as all have mix of head stamps. NO bxn or P, PS or Z codes, but the geometric shapes, O, X, circle with arrow, triangle and diamond were in mix.) The box with red seals was a mic\x of makers three as I recall. (Di\ont have in front of me at moment. Wondered if the Red Seal had any meaning? I dount it but?/ I should add except for one steel case round w Ni Jacket, all were Brass case w mix of GM and Ni Jacketed bullets. HAvent had time to see what if any additions to collection. Any Commentys (BTW strippers in one box were Blue/Black color wityh X 51 the other box had bright Ni plated w no markings.