The 2 sitings appear to be made by a husband/wife who live on DB street and Motorcycle dude riding 3-4 miles away. I think its relevant since we don't know that the couple knows the other man who told LE about Tshirt clad man carrying baby in diaper on that cold night. Descriptions were the same for male build, baby, clothing. For that reason, I think its believable.
The problem I have with Motorcycle sighting is that it was made A WEEK after the face AND after A LOT of media attention.
I think LE have checked out both so-called sightings and found evidence to eliminate both.