Number mix-ups are not uncommon on early C96 pistols. But these mix-ups are usually restricted to swapping numbers, like 96 instead of 69, as a result of the use of unskilled (read: illiterate) work forces in the early days. With the improvement of the education system and internal quality control, this problem gradually went away and I would be very weary of a later C96 with more elaborate mismatched numbers
Mauser never really bothered to keep track of serial numbers anyway. They just numbered batches for contracts or commercial sales and moved on to the next batch, without keeping track of serial numbers they had already used. The sales books only recorded the quantities, never the serial numbers of the C96 pistols.
So anomalies can be expected.