Web and mobile subscriptions

Hi. We have two forms to subscribe for a newsletter on our website – one form is on mobile version and another on regular website. The difference between these two forms is that in a form, which is on a regular version of the website there are two fields (First name and email) and on mobile version we have just one field (email).

Users, who subscribe to a newsletter via regular website’s form are put under “Regular subscribers” list. Users, who subscribe to a mobile form are put under “Mobile subscribers” list.

The problem appears when user first subscribes to a mobile newsletter and then to a regular – his name’s info is not updated and stays empty. How could this be fixed?

https://ww.wp.xz.cn/plugins/wysija-newsletters/