Possibility of getting two USED transmissions that are both bad is pretty high. First thing to fail in a SOHC honda gearbox is the input shaft bearings. Try this...with your car idling, transmission in neutral...push in the clutch and hold it there for 5 seconds or so. Then let it pop up. If you hear a distinct hiss or whirring sound right when the clutch engages, the input shaft bearings are bad. Now, Push the clutch in again. If that same sound goes away when the clutch is disengaged, that verifies that it's the input shaft bearings.

You can detect bad countershaft and final drive bearings while you're driving the car. You'll hear the same kind of buzzing, hissing or whining sound while the car is in gear and driving, and it will be louder in certain gears depending on which bearings are bad. For example, my last transmission had a failing countershaft bearing on the far end by 5th gear. I could tell because, as soon as I shifted into 3rd gear, I heard a faint buzz. 4th gear, the buzz got louder. 5th gear, I could hear it over the stereo.

Unfortunately there's no way to detect these things until the transmission is installed. If you've gotten two bad trannies from the same shop, I'd say its time to find a new supplier.