I was executing patches before updating to 7.10 & 7.11. Execute them in ascending order by version number and found the below duplicate index in the scripts. I have downloaded .zip file from the nexus repository
create index ACT_IDX_HI_IDENT_LNK_TIMESTAMP on ACT_HI_IDENTITYLINK(TIMESTAMP_);
we port database fixes back to older versions of Camunda if needed. This leads, like in your case, to duplicates. In our documentation, we have a list of all patch scripts in which you can also see what patches are equal. https://docs.camunda.org/manual/7.11/update/patch-level/#database-patches
In your case, the patches engine_7.9_patch_7.9.11_to_7.9.12.sql and engine_7.10_patch_7.10.5_to_7.10.6.sql contain the same fix. Since you already executed the first, you don’t need the second.