Yeah, if your B12 levels are that high, you likely have a methylation defect that is preventing you from processing it correctly. The methyl B 12 and methylfolate is actually meant to make your methylation cycle work properly, so that should be OK.
I would read this page:
http://www.stopthethyroidmadness.com/mthfr/
"You can find yourself with high folate or high B12 i.e. your body will have problems converting inactive forms of folate and B12 to the active forms. So the inactive folate or B12 will simply build up in your serum, also inhibiting the active forms. Most serum folate tests are actually measuring folic acid, which needed to be converted to methylfolate to be used metabolically."
This may also help
http://howirecovered.com/active-b12-therapy-faq/