Starting with the release of Strategy ONE (March 2024), dossiers are also known as dashboards.
SYMPTOM:
Custom group name displays twice in waterfall graph on Strategy Web 10.11 while it works well on bar graph.

STEPS TO REPRODUCE:
1. Create a custom group with attribute Category. For Element 1, set the element option to Display element name only(Default)

2. Create a Report with this customer group and some metrics
3. Create a Dossier with the above report. Create one waterfall graph and one bar chart graph. Notice the Element 1 displayed twice in waterfall while it works well in Bar chart.
CAUSE:
This is a known issue to Strategy Web 10.11 and has been addressed in Strategy Web 11.0, please upgrade to this version to take advantage of the fix.
KB442402