Different harps, same key, different pitches

Kinya,

Hope all is well. David suggested I contact you.

I got a tuner app called Soundcorset and used it to compare the 4 blow on my three A harps. I tested each by closing my eyes and playing each harp 3 times in order to ensure a fair reading. Each was somewhat off. I’ve emailed screenshots of the three results to David as I can't seem to figure out how to post in this forum. If you can't get them from David, let me know where I can email thenm to you.

All are a bit sharp, but the Manji is the most acurate, while the SP20 is middle and the Rocket the sharpest. Given that I'm attempting to learn bending and that bending makes the notes flatter, starting off with sharper notes would seem to make the process more difficult, I would think. 

Do you have any explanation for this phenomenon? FWIW, the app calibrates A4=440Hz. 

Thanks in advance,

Ace