What would cause both my front hubs to be.

Depends what you mean by "damaged". Repeat bearing failure is caused by pressing on the center portion instead of the outer ring, or by placing the vehicle's weight on it before the axle nut is torqued to specs. Pressing on the center of the bearing forces the marbles into the race which makes many little dents that cause a humming sound. A similar thing happens when the bearing has to support weight before it is held together by the axle nut. Often people set the vehicle on the ground to hold the axle from turning while they tighten that nut, but that's too late. It's far easier to stick a punch in the cooling fins of the brake rotor to hold the axle while the nut is tightened.

That torque value is critical too. You must tighten the nut with a click-type torque wrench. Most bearings call for around 180 foot pounds, but some go as high as 240 foot pounds.

It also is impossible to remove pressed-in bearings, then reuse them. They must be damaged to be removed, but there is no reason to remove them except to replace them.

You won't see the dents. Those are microscopic indentations on the precision-machined races the ball bearings ride on. When you take a noisy bearing apart, or when it falls apart during removal, you will not see or even feel those dents but you can sure hear the results of them.

I'm not sure what you're referring to about the new bearings being "machine-pressed" in. They are at the factory to save time but not in the repair shop. There are special tools made to make removal of the old bearings easier. A different tool is used to install a pressed-in bearing. Some shops don't have that tool so they take the entire strut off the car and use a hydraulic press. That's like taking the engine out to do a tune-up, ... Serious overkill, but it does get the job done. Many shops no longer have the tools because most car manufacturers started using bolt-on bearing assemblies by the late '80s and early '90s.

You still haven't said what the problem is. You're concerned with some machine that doesn't exist in the repair shops but you haven't indicated what problem is occurring. Are the new bearings noisy? Are they sloppy and allowing the wheel to wobble? What does your mechanic say about the repeat failures?

I don't know if this applies to your car but some axle nuts are what they call "torque to yield" and are a one-time-use nut. The threads stretch once when they're tightened and won't tighten properly the next time. Those are supposed to be replaced with new ones each time they're removed. Regular nuts that do not have to be replaced each time will have slots for a large cotter pin to go through or a stamped steel cap that goes over the nut for the cotter pin to go through. If the nut is slotted always tighten it to the specified torque, then if the slot doesn't line up with the hole in the cv joint, always tighten it a little more. Never loosen a nut to get the cotter pin in.

There will be a large washer under that nut. If that is missing the nut will probably reach the end of the threads before it gets tight. The only other thing I can think of to let the nuts work loose is if the threads on the cv joints are damaged preventing the nuts from going on all the way.

Remember too that the torque value on those axle nuts is very high and the proper tightness is critical. You need a click-type torque wrench to set them. Those can cost hundreds of dollars for real high-quality ones but Harbor Freight Tools has a decent one for around 20 bucks. Sears will have them too but you don't want the less-expensive beam and pointer-type. They aren't nearly accurate enough.

The bearings will come with a sheet of instructions that state the torque value.

It depends on what is damaged and what's causing it. That washer I referred to is only needed when it was installed at the factory. It's not something that has to be added. It is something that could potentially be over looked and left off if the mechanic isn't paying attention. That could make the nut appear to be tight but only because it ran out of threads, not because it is actually clamping anything together.

Many of the torque-to-yield nuts don't use separate washers. They're built into the nut.

The socket isn't the issue when tightening the nut. It's the wrench. The only proper handle for that socket is the click-type torque wrench. It physically clicks when the proper tightness is reached. You can feel it and hear it. Guessing with anything else is completely unacceptable because the torque value for these nuts is critical to the survival of the bearings.

I was going to suggest that but we still aren't sure of the cause of the problem. Your best bet is to find a pick-your-own-parts salvage yard. If you're between Ohio and southern Georgia, do a search for "Pull-A-Part". I've been to 16 of their 23 yards. All are very clean and well-organized. Employees and customers are very friendly and parts are real inexpensive. You pay your buck, throw your tool box in one of their wheel barrows, and you can spend all day there. You can search for vehicles like yours on their web site.