Free trial period with Introductory Offers and Promotional Offers in the same time.

In the condition below, how long is user's free trial period as a result ? Total 2 months? or total 1 months and 10 days?

1. A user bought a subscription plan with 1 month free trial period by Introductory Offers.

2. After 10 days later, the app showed another 1 month free trial as a Promotional Offer to the user and he accepted and applied the offer.

Is there any negative point for user, if we provide a Promotional Offer when a user is yet in Introductory Offers period.