Both with no collars! I'm just wondering if they weren't dumped on that highway and that is why they wanted to go back there.
Have you called the local police station? Around here people will often report a missing or found dog to the police.

These are certainly two darling little pups who should have no problem finding a good home if they need one. What sweeties.

A big thank you from me for saving their lives. You are a hero.