You can do two things:- 1. Either you delete the old prints and set the new one. 2. Either you have to wait for stable update as this bug is reported by various A50 users.
Please perform the following steps to resolve the issue: 1- If any screen guard/tampered glass/protection film is available then first disable the fingerprint settings and then remove the screen guard. 2- Once screen guard is removed now register the fingerprint again and check the issue. 3- If problem does not get resolved, run the device in Safe mode and reconfigure the fingerprint.
4- Check for the latest device O/S (Scroll down Notification panel >Settings >Software Update >Download updates manually).
If still issue persists, kindly visit the nearest service center for physical inspection of your device. Service center personnel will provide you the further resolution. Follow the link mentioned below- http://www.samsung.com/in/support/servicelocation/
