Erik Buck #50 armchair  

And the joinery. On the...
And the joinery. On the left: the fingerjoints, which are a little hard to see. On the right, the pegged butt joint, which is slightly loose, so it is very easy to see.

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Hello Leif, I can give only some suggestions because I've never seen the version without fingerjoints.
It's pretty safe to say that Oddense Maskinsnedkeri never used stamps but only paper labels or in other words I've never seen stamps on Oddense Maskinsnedkeri items.
But Povl Dinesen did signify their items very often by using a stamp.
This fact could tempt me to the statement that the one without fingerjoints is made by Dinesen.
Under the usual reserve.

Thanks Onno. It certainly is...
Thanks Onno. It certainly is a tempting conclusion. By process of elimination it seems inevitable.
Oh, and I found another with the butt joints and stamp that is advertised as Povl Dinesen production.
So there are more of them out there.
I haven't seen many Povl Dinesen stamps, but I remember his name on them, not just the Danish Furniture Control circle. Are there any known Dinesen productions with just a Furniture control stamp?
http://www.zandersandsons.co.uk/product/erik-buck-desk-chair

As I was researching some...
As I was researching some other Povl Dinesen piece, I came across a Buck #50 chair listing from Metro Retro in Texas. Not only do these photos have a Dinesen foil label and butt-joint details, but they also show some slight variation in framing design, including a different rear arm rest connection.
While there's little doubt that a Dinesen cabinetmaker piece has more value than a mass-produced piece, I think the OD Mobler version has more elegant lines. Perhaps it's just the specific camera angles for the shots I am comparing.

That is an odd chair. ...
That is an odd chair.
The #50 I am sitting on right now that I think is likely a Povl Dinesen manufactured chair has the same form as the OD Møbler/Oddense Maskinsnedkeri version. The only difference is the joinery and impressed stamp.
I don't really know what to make of this one that you've found. The level of difference are almost enough to make it look like a different chair.