Two Identical Muskin sticks are obviously different!

I just ordered two 256 Meg sticks from Newegg of Mushkin PC3500 Level II memory. One stick has what appears to be a copper heat spreader and the other has what appears to be a black anodized aluminum spreader. The copper stick feels heavier. They are both labled identically and, on close inspection, only the heat spreaders appear to be different.

Is it usual to receive two supposedly identical memory sticks that are obviously different. Is there any reason to believe that the less massive black anodized aluminum spreader will perform differently than the more massive copper spreader? I intend to call both Mushkin and Newegg later today but I am interested if anyone else has run into this also. There is no obvious problem but receiving two sticks of memory that are not truly identical make me uncomfortable.

Well, Mushkin offers multi-colored heat spreaders, but they should be of the same material. But you should, as you said you were, contact Mushkin. Contacting Mushkin would be alot more helpful then contacting Newegg.