Never heard anything about a Mannlicher-Schoenauer Modell 1906. Sometimes some confusion comes from the Steyr habit of marking their militaryy production. Many M1903 rifles in 6.5x54 M-S from the cheaper miltary production line were imported by British gunmakers like Gibbs, Jeffery or H&H, and converted by them into sporters, some to other chamberings. Mannlichers always had the model designation marked on top of the Receiver ring. Military rifles by Steyr were usually marked additionally with "Steyr" and the year of production on the left receiver wall. Sometimes the Brits scrubbed of the model designation from the receiver ring, but left the date on the left wall intact. My own British Mannlichers by Gibbs are marked this:
M95 Mannlicher, receiver ring scrubbed, left wall "Steyr 1899"
M1900 M-Sch, ring "Modell 1900", wall "Steyr 1901"
M1903 M-Sch, ring "Modell 1903", wall "Steyr 1905"
So IMHO someone read "Steyr 1906" on the receiver wall of a British sporter and mistook this for a model designation.