Disclaimer: Yes, I know that this is not Python code. It just popped into my mind and I simply had to write it down.
The simplest way is the use of shell expansion:
$ echo MPP6R-09RXG-2H{8,B}MT-{B,8}K{H,N}M9-V{6,G}C8R
MPP6R-09RXG-2H8MT-BKHM9-V6C8R
MPP6R-09RXG-2H8MT-BKHM9-VGC8R
MPP6R-09RXG-2H8MT-BKNM9-V6C8R
MPP6R-09RXG-2H8MT-BKNM9-VGC8R
MPP6R-09RXG-2H8MT-8KHM9-V6C8R
MPP6R-09RXG-2H8MT-8KHM9-VGC8R
MPP6R-09RXG-2H8MT-8KNM9-V6C8R
MPP6R-09RXG-2H8MT-8KNM9-VGC8R
MPP6R-09RXG-2HBMT-BKHM9-V6C8R
MPP6R-09RXG-2HBMT-BKHM9-VGC8R
MPP6R-09RXG-2HBMT-BKNM9-V6C8R
MPP6R-09RXG-2HBMT-BKNM9-VGC8R
MPP6R-09RXG-2HBMT-8KHM9-V6C8R
MPP6R-09RXG-2HBMT-8KHM9-VGC8R
MPP6R-09RXG-2HBMT-8KNM9-V6C8R
MPP6R-09RXG-2HBMT-8KNM9-VGC8R