Actually this is a common practice for glass makers just to over strike the older date each year. I've found this on several bottles over the years, and even my 1954 has the 4 struck over top of the 3.
It actually looks like a 1955. Instead of creating a different bottom mold for each year they would just stamp the new date over the old date. That's the best guess I can give with the pictures provided. Usually the newer number is the actual number.
I know this is mostly a 'Dew' thread but wanted to add my list of King Cola bottlers. I included Covington, Culpeper, ad Winchester from your article that were new to me.
King Cola Roanoke VA
King Cola Salem VA
King Cola J. C. Layman Co Bristol VA
King Cola McClure Bottling Company Haysi, VA
King-Cola The Royal Drink - Frank Wendell, Cape Charles, VA
King-Cola Bottling Corp., Lynchburg, VA 1916
King-Cola Bottling Co., Edinburg, VA 1916
King-Kola - Peninsula Bottling Works, Parksley, VA
King-Cola Bottling Works Phoebus, VA
King-Cola Bottling Co., Weyers Cave, VA 1917
King Cola Marion Bottling Works VA
King-Cola Norfolk VA
King Cola Covington VA
King Cola Culpeper VA
King Cola Winchester VA
Richmond-Washington King Cola Bottling Company Inc
Richmond VA June 8, 1917
King Cola Kehne Brothers Frederick MD
King-Cola Sanitary Beverage Supply Co Charleston WV
King Cola Charlestown Bottling Works Charlestown WV
Greensboro King-Cola Bottling Co. NC
King-Cola A. L. Harrington & Son Kinston, NC
King Cola Bottling Co., Durham, NC 1916
King Cola Bottling Co., Oxford, NC
Albemarle King Cola and Dixie Flyp Corp C R Pugh Elizabeth City NC 1920