Can neurofibromatosis type 1 progress to neurofibromatosis type 2?

NO . Tow distinct gene mutations. Neurofibroma nf i & nf ii are both inhirted tppe i will show cutaneous, neurological and ortho malformations.Tend to be non cancerous nf ii is less frequent ( i in 40000 ) less skin lesions more neuroligical tumors, like maningiomas, bil aucoatic neuromas, schiwanomas, gliomas is part of misme syndrome.
Rare. Extremely rare to have nf1 and nf2 at same time. Not sure if this combination has been reported.