2002 Dodge Grand Caravan brakes are not.

When they lock up, crack open the steel lines at the master cylinder to see if any trapped fluid pressure releases.

That is tentative good news as it does not definitely indicate brake fluid contamination. That is an expensive problem.

Open the bleeder screws on the calipers to see if they release. If they do not, the pistons are sticking in them. If they do release, suspect the rubber flex hoses. I suppose there could be internal leakage in the anti-lock brake hydraulic controller if you have ABS but that's not really a problem I've heard of.

Do you have anti-lock brakes?

Go all the way up to the hydraulic controller and crack open the lines to see if the brakes release. If they do, I suspect this might be one for the dealer. Unlike some older systems, there is no brake fluid stored at high pressure so leakage in a valve shouldn't be a problem, however, I suppose a valve could be blocked and not allowing the fluid to go back to the master cylinder.

The base hydraulic system is still a split-diagonal design with the two front brakes on different circuits. They each also have their own circuits during an ABS stop. That would imply there would have to be two blocked passages in the controller or a blocked passage that is common to both front wheels. That's assuming, of course, that both front brakes are locking.

This isn't something I've run into before. I hope I'm wrong about it needing a controller.

When you said you replaced the lines, I assumed you meant the rubber flex hoses. Is that right or did you mean the steel lines?

When a caliper is locked up, start up higher, like by the controller, and crack something open to release the trapped brake fluid. Work your way down until you find the point where it releases. That will be the point of the restriction. If you find a metal bracket crimped around the middle of a flex hose, that is where rust likes to build up and constrict the hose. Peeling that crimp open just a little with a large Channel Lock pliers will solve that one.