The nice thing about ancient coins (including medieval) pre-machine coins is that the dies were individual works of art (no "hubbing" etc.). Therefore I never have a problem with duplicate ancients in my collection. They are all different (not counting die-matches, of course). Other factors come in as well - I have an inexplicable attraction to off-center ancients. Also, as with Alegandron above, I love banker's marks (and Chinese chopmarks on moderns - I spent many years hunting those down). Not to get high-falutin' but I think of ancient coins as individual works of art...not possible with a bunch of machine-made Morgans. One individual Morgan pretty much covers the lot in terms of appearance, until you start counting tail feathers and tiny variations that have to do with technology (over dates) than an actual engraver (artist). Nothing against Morgan collectors - besides, I have no room to talk - the bulk of my collection consists of modern foreign crowns, rows of Prussian 5 marks that all look the same except a couple digits in the date, six 1953 Cuban pesos, all vaguely "upgrades" etc. I spent years on this stuff. I will weed out ancients that are too similar to something I already have or simply too ugly or crusty to want to keep if an upgrade comes along (sometimes I don't wait for an upgrade - if it doesn't please me, why keep it?). Or, sometimes, if I paid too much for something and the sight of it makes me cringe - I'll get rid of something like that too. By the way, I really like all these M. Aemilius Scaurus and Pub. Plautius Hypsaeus denarii you all posted. I don't have one, sorry to say, but if one comes within my budget, I will certainly snap it up.
I'd keep them both. The camel and saddle on the first would be too good for me to give up, if I had the means to hang onto both. Besides, having doubles lets you pretend you're holding pocket change a long time ago, instead of collecting coins from a long time ago.
I had one with REXARETAS on the flan but the camel's head off the flan. I upgraded to this one: Everyone says it is hard to find an example with everything that is on the busy die actually struck on the flan. I didn't manage to get one.