The Login One! plug-in does not interfere with the creation nor with the maintenance of user accounts; it only acts during the authentication process when a user logs into the website at the front-end. So I do not see how it can replace existing accounts.
If you want me to look deeper into it, I would need a temporary admin access to the back-end of your website. You can email me at This email address is being protected from spambots. You need JavaScript enabled to view it.

Joomla! version: 2.5.4
PHP version: 5.2.17
MySQL version: 5.0.95-community
Akeeba Subscriptions version: 2.2.1

Login One! pulgin version 1.1.0.1

We tried to buy several subscriptions (for different users) in the same computer and Internet browser, subscriptions were recorded but only one user created; new subscriptions just replaced the same user's record in Joomla users list
akeeba subscriptions normaly leave the user logged in after checkout, this is not reflected due loginone plugins conflict (apparently theres is no open session) and the system lose control of the session, replacing data from previous subscribtion ("current") user when new subscription is made


TURNAROUND
after a subscription/checkout is made, a manual login/logout "reset" the subscription form, allowing new subscriptions and users be created