Prosites trail number of days doubled

Hi there, I have setup a 15 day trial for my users in Prosites in the settings section.

However when the user blog is created, the user is allocated a trial for 30 days.

I re-checked with 1 and 3 days of trial in the prosites setting.

When the trial period is set 1 day, the user is allocated 2 days of trial.

And When the trial period is set as 3 days, the user is allocated 6 days of trial.

Can you please suggest what may be the problem?

Thanks, Best Regards,