Date & Time: 4/21/2022 1:21PM EDT
Frequency: Intermittently
World name: Brynhildr
Character name: N/A
Retainer name: N/A
NPC name: N/A
Monster name: N/A
Class/Level: 1
Party or solo: Solo
In-game time: N/A
Area and coordinates: N/A
Housing: N/A
Steps:
1. Create or Load Appearance Data
2. Browse Eorzean Calendar Dates
3. Check if any namedays are duplicated dates when selected (most often occurring in 7, 8, 28, 29, 30 for me)
4. If no dates are duplicated, load character again
5. Check if namedays duplicated

The namedays are not duplicated once finalized on the character select screen.