It may be redundant, but independently of this the real conrcernconcern should be to evaluate if this redundancy is beneficial, harmful or neutral.
Different goals, different designs
Do you need a confirmation modal or just an informative one?
Confirmation: To start with you'd need a OK/Cancel pattern which will offer a clear binary option. You could avoid the X button here but I see no reason to to do it, since it can impact in the user flow if they are used to close everything with it.
Informative: Is it always necessary or recomendablerecommendable for the users to actually read the message?
Yes: Don't place a X button nor a Close button, because you don't want to give the user the easiest and fastest way out. Place one "OK" / "Got it!" button so the user is less likely to pass over the message. Also you should take care of the "clicking outside the modal" in this case.
No: Place both an OK or Close button plus a X button. Simply because thereThere are different types of users with different interaction habits, so there's not a good reason just to cut off the best natural flow for each one. Moreover if the message is not very important you should ask ....
Is the modal really necessary?
If your goal is to inform the user, there are more unobtrusiveless obtrusive options like notifications,such as notifications; try to limit modal use justto when it is really necessary. Examples from the NNNielsen Norman Group article:
- The user is about to take an action that has serious consequences and is difficult to reverse.
- It’s essential to collect a small amount of information before letting users proceed to the next step in a process.
- The content in the overlay is urgent, and users are more likely to notice it in an overlay.