Doofenshmirtz is probably the ancestor of the modern day Heinz Doofenshmirtz and a nemesis to the Perry the Platypus of 1914, and Ohio Flynn & Rhode Island Fletcher. He was the main antagonist in the episode "Phineas and Ferb and the Temple of Juatchadoon".
Doofenshmirtz displayed little of the childlike traits of modern day Doofenshmirtz, making him far less of a comic villain, and more of a serious one. He is also a lot calmer, as he did not react to the Abominable Snowman's presence and was focusing on Ohio and Rhode Island instead. Doofenshmirtz was also observant enough to notice the Abominable Snowman, and calm enough to conclude that the giant dining set belonged to the monster.
He seems to be durable enough to take a beating from a giant bipedal ape at least twice his size. He is also very intelligent but has not built any of the impressive machines that his descendent has, with the exception of a rocket sled.
Judging from Ohio's recognition, it would seem that Doofenshmirtz had at least one encounter with the boys prior to the events of "Phineas and Ferb and the Temple of Juatchadoon".
Perry the Platypus
Judging from the recognition of Doofenshmirtz to Perry the Platypus, it would seem that they had at least one encounter prior to "Phineas and Ferb and the Temple of Juatchadoon". However, Ohio and Rhode Island didn't seem to be aware of Perry's existence until the episode. It is assumed that they both died after the events of the episode.
Doofenshmirtz abducted Isabella's mother, and blackmailed the girl into aiding his search for the Amulet of Juatchadoon in exchange for her mother's freedom. However, he then double-crossed her, and Isabella helped his nemeses Ohio and Rhode Island to thwart his plan.
- The winter coat that this Doofenshmirtz was wearing is similar to or the same as Heinz Doofenshmirtz's winter coat in the modern day.
- It is assumed that, along with Perry, Doofenshmirtz died after the Temple of Juatchadoon was destroyed, this would make him the second Alternate-Doofenshmirtz to die (assuming that Dr. Jekyll Doofenshmirtz, from "The Monster of Phineas-n-Ferbenstein", was eaten)
- Instead of a labcoat, Doofenshmirtz wears a suit, tie and hat covering his hair, which seems to be more tidy than the modern day Heinz.