Open your report in Visual Studio and under Parameters node, check if your parameter is repeating. If yes, delete one.
Most of the time it happens during development when you are changing code again n again. It cahces your previous code and shows new and previous both.
In this case :
Clear all of your caches from AOT.
It it doesn’t work, run incremental CIL.
It it doesn’t work, try deleting .auc files.
At the end, try redeploying the report.