Cardio twice a day is fine, assuming you are not really pushing it to very high heart rates both times. If you sit all day at work, some low level cardio is not much different than people who actually work on their feet, nothing wrong with getting everything moving. I recommend a class like zumba, so you are not doing the exact same exercise if you usually bycicle or treadmill. Zumba works a variety of your muscles, rather than something like running, that is the same muscles over and over and over again. There are some stats that doing aerobics for a long time actually can have some negative impact, I can try to find it. But, if you are just moving, low impact, and only raising your heart rate minimally, it would not fit into this stat in my opinion, and it will continue to help you lose weight.
For stregnth training, you have to let the muscle rest to build and repair. You shold not be working with weights on the same muscles groups daily, especially not twice a day.