When the mints transitioned to the one-standard types, you also find varieties with a chi-rho on the banner, but I think the two-standard chi-rho coins are much rarer.
yes the chi rho on banner are very common, I have probably over 100 of them, but try and find one of these to buy.....it isnt as easy as some people might think. I think its because there was a very small window in 334 I think, although I'd have to check.. where they minted 2 standard with chi rho before moving to the 1 standard chi rho
The 'gem' arrived today... needed a light clean, but I am happy . Better pics to come, for now just a quick phone shot. it's got some nice silvering on it which is nice and the chi rho is sharp...another bonus.