To my way of thinking, yes, it's an overlap, mainly to the 6.5x55, of course. But if you want it, get it.
My deal was, some years ago, I HAD to simplify on *some* basis, but I liked all my rifles, so one of the bases I came up with was "no odd-numbered calibers": Even numbers were OK: .22 cal, 24 cal, 26 cal, 28 cal, 30 cal, which also coincide (roughly) with the nice even names of 5.5mm, 6mm, 6.5mm, 7mm, and 7.5mm. (Not really because .308, as but one example, is actually 7.82 under english/groove measure, and 7.62 under european/lands measure, but we'll pretend these are all rounded to the nearest 0.5 under land/euro measurement, which they are commonly known as, in fact)
So the oddballs had to go: .25s and .27s (6.2mms & 6.8mms). So I bid goodbye to my beloved .25-'06 & .270 win rifles. I kept .223, .243, .260 & 6.5x55, .280, and .30-'06.
I'm happy with my decision, though the .270 WSM and Nosler Accubond LRs in .277 made me briefly re-consider. But the .26 Nosler can scratch that itch if need be and still stay within my OCD-induced scheme.
Thankfully, I've decided to "round" my .375 HH mag rifle to being in the .38 cal & 9.5mm categories. I would lose sleep if I thought that this was a .37 cal or a 9.4mm rifle!
Technically, this may belong is the "General" rifles area, since it's single shot question.
I like those No. 1s and love the 6.5x55. Let me know if you sell.
[Sidebar: Actually, now that I think about it, I just realized that the 9.3x62mm cartridge is not named correctly. It's clearly a Euro cartridge, through and through (correct?). And Euro cartridges always used the land measurement, expressed in mm, which would be about 8.8mm, not 9.3mm. The groove is 9.29mm or 9.3, but that's the American or English convention! So it should be called the 8.8x62mm - what gives?]