An Aulos recorder will not be at A=415 pitch, they only made the modern pitch ones.

Yamaha have made a few very expensive hand-finished wooden models at A=415 pitch, and a transverse flute with interchangeable parts to allow both A=440 and A=415, but their ordinary plastic moulded stuff is all A=440. Both firms are reliable mass producers so everything they sold anywhere in the world will be the same.

I think the only mass-produced A=415 recorders of the last 40 years have been unbranded (my purple oddity is like that, though it looks like a Yamaha in basic shape).

You are warming them up properly before you play? - Aulos instruments are particularly prone to playing flat when cold. And you're blowing hard enough? If so, I would suspect your tuning reference rather than the recorders.

Have you tried the recorders and your tuner against the tuning reference on my website? - in effect this is checking them against your own computer, since it's done by MIDI and QuickTime rather than MP3, but it would provide another reference point. Tuners are OFTEN wrong - when I get to be dictator I'll have them all scrapped.

Which notes are you checking? The G on a soprano and the C on an alto (i.e. thumb and three left hand fingers down) are the easiest to get stable.