At first I want to inform you, that the correct spelling of "Opel & Beyschlag" was ever and is: Opel & Beyschlag! For 100 percent sureness.
Secondly, in my opinion, there is a linguistic misunderstanding, depending the 'reading the statistics of the 'Semmering Rennen 1907':
Opel & Beyschlag's Darracq (Robert Koch), means: Entered by: Opel & Beyschlag (correctly written!), Car: Darracq, Driver: Robert Koch
Compare with line above:
Max Klug's Sizaire & Naudin (Max Klug), which means: Entered by: Max Klug, Car: Sizaire & Naudin, Driver: Max Klug
In my opinion, 'Opel & Beyschlag' never produced cars. Only motorcycles (1904+). But I will go on searching. Sometimes miracles will happen...