Can neurofibromatosis type 1 progress to neurofibromatosis type 2?

No: Two distinct diseases caused by different genetics.

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.