I'll try my best, but I'm not a tech expert.
You sent Payment A and B with different fee. A few was higher and B was very low fee. Payment B was first removed from the Bitcoin network and dropped, because its fee was too low probably when there was a congestion in the network.

Bitcoin miners prefer transactions with higher fees. When you sent Payment B again with a higher fee, miners accepted it, and it was then added to a block with Payment A.