Thanks for all your replies! As a new investor, I appreciate the interest in this topic.
Lot 2 was purchased before sale of lot 1. Both were there, only I could not choose the one I wanted to sell.
I never, ever, thought of selling at loss as a beneficial situation. But several replies are pointing in that direction. My aim was to wait long term until lot 1 was profitable, since I did not need the money, but I guess it is common for investors to sell at loss purposedly for tax writeoffs.
It also seems clear that Zecco does not offer the option of choosing specific lots, after all.