Something strange I noticed about 1888 Goodwin Champions

Has anyone else noticed the subtle differences on the backs of the 1888 Goodwin Champions cards? One version has two lines at the bottom which read, "Goodwin & Co." with "New York." underneath, while the other includes a 3rd line which reads, "Geo S Harris & Sons, Lith Phila.". I found this interesting so I did some research (like 15 mins worth) and have only found two baseball players (Glasscock and Keefe) so far that I can confirm being found with both back variations.

Does anyone know why the difference and is this something that has been discussed before? I find it rather interesting and wonder if these two variations might have been printed in different locations or if one might be more rare than the other?

Here's a link that will allow you to quickly see what I'm talking about. It does not include two different examples of the Glasscock and Keefe but I was able to locate each on cardtarget.com.

http://www.tradingcarddb.com/Gallery...hampions-(N162)