The truth is, it's not just Disney who can't really file lawsuits against other companies because of eerie similarities, that's just how the business works - television and movies have a tendancy to carbon-copy themselves, they always have, and they always will, and there's really nothing that can be done about it, although some HAVE tried...
Aside from JHC suing the producers of Wimzie's House for an unknown motive (they said it was because the characters looked too muppety, but then again, look at shows like Between the Lions, etc); the producers of the epic WW2 movie Stalag 17 sued the producers of Hogan's Heroes, because the show was essentially a rip-off of the movie - both set in German prison camps, both had put-upon Kommandants, both has Sergeants-of-the-guard named Schultz, both had savvy con-artists of protagonists, etc. Unfortunately, the producers of Stalag 17 were unsuccessful in their lawsuit.
After Bewitched became so popular after its first season on ABC, NBC immediately tried to cash in on the premise of a magical sitcom, and commissioned Sidney Sheldon to create I Dream of Jeannie, and Sheldon himself actually consulted with Bewitched director William Asher, admitting he was working on a "rip off" on how to put the show together. Sometimes, two parties like that can actually work together in a professional manner - M*A*S*H and Hogan's Heroes had some of the same staff members.
We're all familiar with the movie Twister with Helen Hunt and Bill Paxton, right? With that severe outbreak of tornadoes in the midwest? Well, did you know that very same year, there was a TV movie made called Night of the Twisters? With a smalltown bracing itself for a severe tornado outbreak? Or how about when we got Happy Feet in 2006 about a penguin who loved to tap dance, then a year later we got Surf's Up about a penguin who loved to surf? Not only that, but Surf's Up had a character who looked almost exactly like T.R. Rooster.
There's another issue too - characters from different projects that look very similar to each other... in 1988, Murakami-Wolf-Swenson produced half of Season Six of Alvin and The Chipmunks, and that same year, a new character was added to Teenage Mutant Ninja Turtles who was so obviously designed based on Jeanette of The Chipettes. And speaking of which, an artist friend of mine has told me that she once submitted an idea to MWS of a female Turtle character named Mona Lisa, but they told her they couldn't and wouldn't accept ideas like that... but shortly afterwards, saw the appearance of a one-shot character - a female lizard named Mona Lisa, who was essentially the same character.
Rip-offs are a part of the industry, and there's really nothing that can be done about; yes, some parties CAN and might even try to file lawsuits, but they are often times futile, and accomplish nothing. The only time I can think of such a lawsuit working regards Sid and Marty Krofft Vs. McDonalds - McDonalds asked the Kroffts to create a concept for them for their commercials based on Pufnstuf; the Kroffts and their team designed and built the costumed characters (Mayor McCheese, Apple Pie Trees, etc) and the sets, but McD said they decided to pull the plug on the project... that was supposedly the end of that, but then months later Sid saw that McD went ahead with the commercials anyway and aired them. With that, Sid and Marty sued McD, and they actually won the lawsuit, but they didn't receive a settlement until thirteen years later, because they were a small, independent company vs. a big corporation.