I'm sure my 3 year old would love to see the other male dissapear

Kevin, it sounds like the DDR is simply maturing, and is looking to turn the tables on both you and your other male. I have a 3yo DDR male, and was he ever an a$$hole from about 18-28mos. Extremely dominant, started staring contests with men he came across, wouldn't ever allow anyone to touch anything he deemed "his" (which was anything and everything-me included). He's not dog-aggressive, per se; he's just dominant. On neutral ground he's ok with other dogs provided they let him be the boss. His nephew will not even look at a toy if he's anywhere in sight, even in his crate, for fear of serious punishment.

If you let these 2 continue to hang out together, it's going to get ugly. Really ugly. Mine is settling down quite a bit now, but I still wouldn't leave him w/another male unsupervised. Your other dog is being very patient, but believe me; this won't last forever. Your DDR is not a puppy anymore (to the Czech), and your Czech is going to tire quickly of this and take it into his own hands...er paws. My APBT female is the only one to ever succeed in putting mine in his place, and I firmly believe this is because she's female-not that he's learned any lessons. The first time he got nasty with her (during an intro period when I first got her), she ran to me. The second time, she ran at him. He got off easy with *deep* holes in his muzzle, and deep holes through his front leg. He limped for almost 2 weeks and had a big lump on his muzzle for over a month. I thought his leg was broken, but she bit around the actual bone, luckily.

Keep in mind that I was right there, with his trainer when this happened, and this damage was done while 2 adults were pulling these dogs apart. If I'd been alone, I never would've been able to stop them. Not more than 5 seconds passed; imagine the carnage if they'd been left alone. Don't chance it-keep them separated unless you are specifically working them together. Don't let your Czech have any reason to go after your DDR, or you're going to set a pattern that I'm afraid will be much harder to break than if you stop it now.

AMEN to Jenni's post above -- If left to their own devices, the dominant dog will end up either terrorizing OR killing the subordinate dog, IMHO