Set of 2 Stereo Cards Card No. 17(a) "Eavesdroppers" Card No. 18(b) "Eavesdroppers Dropped"
Could be Ingersoll--but not marked.
This type of stereograph lithograph printing became common after 1898 and, because it was simply run off on a commercial press, could be sold for next to nothing. Sears, Roebuck's 1908 catalog offered 100 such views for eighty-five cents. For $1.00 you could have the 100 views plus a stereoscope.