This is XLS version of fixed bug 138181. Open attachment 167271 [details] and see second legend entry visible, it shouldn't be.
Created attachment 167997 [details] Comparison LibreOffice 7.2 master and MSO 2010
Reproduced in Version: 7.2.0.0.alpha0+ Build ID: 84af20ef3ea72190784e9e7be820684c2558ba8c CPU threads: 4; OS: Linux 5.7; UI render: default; VCL: gtk3 Locale: fr-FR (en_US.UTF-8); UI: en-US Calc: threaded