Yes, it is possible to have both options with your request.
In which case, with the premium option, you will need to have at least two translators in your translator list already, and with the double-check option, a request will be translated by one translator and checked over by another translator.
Usually, in the case of a usual request, one character is equals 1.5 JPY*. For a premium request it will cost 1.5 times more than a usual request, and for a double-check request, it will cost double the fee of a usual request. Please note that if you choose the two options at the same time, it will cost 3 times more than a usual request.
*For Japanese, Chinese (simplified and traditional) and Korean, it will cost 6 JPY for one character.
For example, a 100 character request (150 JPY with no options) will cost as below:
With the premium option: 150JPY×1.5=225 JPY
With the double-check option: 150JPY×2=300 JPY
With both options: 150JPY×1.5×2= 450 JPY
＜Option Fee Comparison＞
|No Option||Premium Request
|A Request (100 characters)||150||150||150||150|
|Premium Request Option||0||×1.5||0||×1.5|
|Double check Option||0||0||×2||×2|