Perhaps the 74 days sender is accumulating the good material to meet your profile criteria
and than the 43 days sender had that available stamps by the time he get your address.
Or 74 days sender 1st sent out envelope was return to him due to unforeseen circumstances and thereafter get your address again in different ID, so he might decided to send all out under one envelope to you.
No matter what is the real fact, he has given you a big surprise. Happy ending story.