I found a discussion about ancient uses of the Chi-Rho on web site Historum. I was not aware the Chi-Rho was used by some Romans as an abbreviation for "centurion." Of course it was also used by Christians and Constantine I as a symbol for Christ. Words and symbols can have different meanings and change over time. Here's pics of the sources cited. One is an inscription from Sardis, the other a papyrus in Berlin.
thanks for the article, I did not know that.
the chi-rho was also used on Greek coins for a control mark, maybe the initials of someone.
Ptolemaic Kingdom of Egypt, Ptolemy III Euergetes. Æ Diobol (29mm 21.0gm) Alexandria, circa 245-222 B.C.; Diademed head of Zeus-Ammon right / BAΣIΛEΩΣ ΠTOΛEMAIOY, eagle left on thunderbolt; in front cornucopiae; between legs chi-rho monogram. SNG Copenhagen 176-177.
Yes, I have one of those Ptolemy III coins with chi-rho under the eagle.