Testbench Variables in Ocean Prerun Script

Hello,
I encountered a strange behavior in ADE Assembler with a prerun script for which I could not find any documentation.
I have an Ocean script which is supposed to generated some input files for Spectre based on the current value of multiple design variables. It looks something like this:

ocnxlLoadCurrentEnvironment( ?noAnalysis t)
...set some defaults...
foreach(dvar desVar()
   ...override defaults with 'dvar'...
);foreach

The script itself seems to work fine, but after I deleted some variables from my ADE testbench it started to produce wrong results.
After a lot of debugging and head scratching I found out, that 'desVar()' does not only returns the current variables defined in ADE, but also additional variables directly saved to the testbench cellview.

I usually do not save design variables to the cellview, but it seems this was done automatically after I did a 'Local Optimization' and back-annotated the result.
After I deleted the 'designVarList' property from the cell, the script worked fine again.

However, I now always have to check if the testbench cell has some variables saved in it and manually delete them. 
Is there a way to get only the ADE variables in a prerun script? I checked the generated netlist of my testbench and here only the actual ADE variables are used.

Best regards
Paul