Wassily B3 Chair Authentic? Please Help!  

Hi, Wondering if anyone can shed some light / has any thoughts about a pair of Wassily chairs im looking to buy. Im not having much luck with the seller on getting really useful images but have attached the ones i have. 

Points of note:
-Seller advises they were purchased in 1983 in Australia and in one of the images there is a store sticker from 'Bates Mt Waverley'.
- The leather seems to have a good deal of thickness compared to some cheaper repros
- Tube ends look to be solid rather than caps 
- Leather has a tan sidewall/ profile which i can not find in other examples online
- Allen bolts look flush with frame
- Leather on underside of chairs has not perished
- BUT! tube at the base of the chair (the part that touches the floor) seems to be split in two places rather than one central seam. Has anyone seen this before?

Any thoughts on the chairs would be much appreciated 
Best, 
James