Ah well if you changed the condenser then obviously you had to depressurize the system!
If you did not evacuate the system (pull a hard vacuum on it) first then you have trapped moisture in there that WILL eventually get you. The problem is that the refrigerant + moisture forms an acid and eats the system from the inside out. It's one of the "gotchas" with 134a systems; there cannot be ANY moisture (which has other bad effects in all systems anyway, including freezing up the TXV or evaporator's interior tubes, which is why it was considered "ok" in the trade-offs when 134a was designed) in the system or it will eventually be destroyed.
Replacing the evaporator is a five-alarm pain in the butt (same as heater core replacement; the entire dash has to come out of the car to get to it!)
Assuming you just charged it and didn't pull vacuum (I presume you don't have a vacuum pump) I'd take it to an AC place, have them fully evacuate it, replace the dryer and pull vacuum on it for a solid hour first, then recharge it. If you have reason to believe there's a slow leak then use one can of refrigerant with UV dye and one without so you can easily find it when it leaks down some.
SOME of the dryer dessicants used cannot be renewed. There are plenty of people who believe if you pull vacuum on a dryer for a good long time all the moisture it trapped will be released and removed. Maybe, maybe not depending on the exact dessicant in there, so unless you *know* whether the particular one in question has a dessicant that undergoes chemical change (as opposed to simple absorption) you have no way to know if it's ok to do that or not.
The other problem with the dryer is that it's a fairly decent filter for garbage (sludge, etc) that accumulates in the system over time. They can and DO plug up; a partially plugged one will materially lower cooling efficiency by serving as an orifice in front of the TXV and a really badly-plugged one will make the system inop entirely (with very low high-side pressure.) Since they're also cheap it's poor economy to not change it any time the system is at atmospheric pressure. The only bad thing with changing it is that on the MkIv cars it's a five-alarm pain in the butt to get to the mounting bolt for the clamp and the top bolt for the connection, and you have to be careful with that top one too because it's directly connected to the hard-line of the condenser output. Fracture that pipe and you're now tearing the front of the car off and replacing the condenser.
You can detect a partially-plugged dryer by the fact that the pipe on the bottom (the output) will be cooler than the one on the top (input); there should be no material difference in temperature between them.
The capacity on the sticker is 750g with an error of +50; 2 cans is 680, so you're reasonably close to a full charge and it should work fine with that amount in there. If you want to be right in the middle of the error band put another 100g in from a third can.