If multiple users were enrolled same fingerprints or face, then there can be some security problem. To prevent user enrollment with duplicated fingerprints or faces, duplication check-in BioStar 2 is supported from BioStar 2 v2.7.8. You need to match BioStar 2 server version and device firmware versions to enable the 'Duplicate Check' feature.
Supporting Devices:
FaceStation 2 v1.3.0 and later
FaceLite v1.1.0 and later
BioStation 2 v1.8.0 and later
BioStation L2 v1.5.0 and later
BioStation A2 v1.7.0 and later
BioLite N2 v1.2.0 and later
FaceStation F2 v1.0.0 and later
BioStation 3 v1.0.0 and later
X-Station 2 v1.0.0 and later
BioStation 2a v1.0.0 and later
You can configure for fingerprint/face duplicate check, enable or disable.
It does not have a limitation on whether your device has an LCD or not. (Only needs your firmware to support this feature.)
BioStar 2 - Device - (Selected Device) - Fingerprint or Face/Visual Face - Duplicate Check - Enable / Disable
The default setting in BioStar 2 server is 'disabled.'
<Fingerprint Duplicate Check from BioStation 2>
<Face Duplicate Check from FaceStation 2>
<Visual Face Duplicate Check from FaceStation F2>