On App Install, redirect URL gets called twice intermittently (only on Chrome)

[hiya]

I have a public app approved by Shopify review team. When I try to install this app, sometimes (4 out of 9 attempts) will be unsuccessful. All unsuccessful attempts are when installed on Chrome. However, 3 out of the 5 successful attempts were also from Chrome, so Chrome doesn't always fail to install the app. 

Expected behavior:
When I click on install on the app page, I have logic to get a Shopify offline token from the redirect URL. Once this token is received, user will be redirected to the app site to create an account.
Actual behavior:
When I press the install button on the app page, it somehow calls the redirect URL twice so the authorization token seems used and I get the error: 'The authorization code was not found or was already used'.

Any ideas what I can do to resolve this issue?