In fact, having the swap space twice the size of your RAM is only a guideline. Actually with 8GB of physical RAM you won't need much swap space: you might want to keep the one and delete the other partition indeed. If you want to use swap encryption you should keep the cryptswap if not, the other one.

However, if you ever want to hibernate make sure you have at least 8G of swap.

In fact, having the swap space twice the size of your RAM is only a guideline. Actually with 8 GB of physical RAM you won't need much swap space: you might want to keep the one and delete the other partition. If you want to use swap encryption you should keep the cryptswap if not, keep the other one.

However, to hibernate you must have at least the same amount of swap free as you do RAM used.