I'm not 100% sure and I haven't processed at home yet, but I have seen a lot of negative film with my own eyes, different brands different speeds... I used to care a lot about the colour of the film base, also the actual contrast of the font type on both sides of the frame (normally the brand and the film type) how those letters looked after developing..

Sometimes I received from labs negatives that looked weird or 'different' but at the end all those negs scanned and R4 printed properly... so dunno, I wouldn't worry too much, but I would like to know also from someone that knows for sure...

maybe neg manufacturers use different film base, as long as the emulsion is the same, the base can always be compensated in print (the point of being a negative)

but as I said I am just speculating...