Old, until 2023: After you had a QSO with a station in CW, a QSO afterwards with the same station in SSB counted neither points nor multis.
New, from 2024: After you had a QSO with a station in CW, a QSO with the same station in SSB counts both points and multis (if this WAE/DXCC/DOK multi is new in SSB and not already a third station has assigned this).
The same applies in reverse if you first have a QSO in SSB and then in CW.
Rule change in the DARC 10-meter contest: Mixed mode only. No change in CW-only and no change in SSB-only
The next DARC 10 meter contest is in January 2025. So don't rush.
English: https://www.darc.de/der-club/referate/conteste/darc-10m-contest/rules/ German (the changes in red font): https://www.darc.de/der-club/referate/conteste/darc-10m-contest/rules/
I understand it like this:
Old, until 2023: After you had a QSO with a station in CW, a QSO afterwards with the same station in SSB counted neither points nor multis.
New, from 2024: After you had a QSO with a station in CW, a QSO with the same station in SSB counts both points and multis (if this WAE/DXCC/DOK multi is new in SSB and not already a third station has assigned this).
The same applies in reverse if you first have a QSO in SSB and then in CW.
73 Dieter