The first time you call ServerTravel with a mapname and some options will load the map name with the options as expected. When making subsequent calls to ServerTravel with different options, the new options are appended to the old options. The old options are not removed. Example:
This willl load Level1 and the OptionString = ?LoadFile=Save1
Then you can call ServerTravel Level2?TestParm=MyTest
This will load Level2 and the OptionString = ?LoadFile=Save1?TestParm=MyTest
Note that the LoadFile parm is leftover from the first call to ServerTravel. Expected result is that parm would not be on the OptionString at all.
Note that this only happens in standalone or packaged builds. When running in PIE it works as expected. Also note that calling Open with parms does work as expected with old parms being removed. This only seems to affect ServerTravel.