Just one author in certificate displayed

[hofmannc]

Testserver: qa keeper
Browser: firefox 77.0.1 (64-Bit) Chrome 83.0.4103.61
Version: Seafile 7.1.3

Actions: enter two authors in archive-metadata.md following this pattern:

Observation:
Certicifate only displays one of the authors

Question:
Is this the correct entry pattern?

Expected result: All authors are displayed or something like "et al"