Any way of combining two MBL drives?

If i understand correctly about what you are asking, You want to combine both of the volumes into 1 for a 2TB drive instead of 1TB without buying a separate drive.

While I am not 100% sure, I have researched this topic and have not found any possible way that this can be done. The only way you can merge the drives into 1 would be on your computer; and if it has RAID capabilities.