Just tried this out on my local Umbraco dev install (using SQL CE4) and got the following error in the Prevalue Editor:

Error running NonQuery: 
SQL Statement:
insert into cmsDataTypePreValues (datatypenodeid,[value],sortorder,alias) values (@dtdefid,@value,0,'')

Exception:
System.ArgumentException: The SqlCeParameter is already contained by another SqlCeParameterCollection.
  at System.Data.SqlServerCe.SqlCeParameterCollection.Validate(Int32 index, SqlCeParameter value)
  at System.Data.SqlServerCe.SqlCeParameterCollection.AddWithoutEvents(Int32 index, SqlCeParameter value)
  at System.Data.SqlServerCe.SqlCeParameterCollection.Add(SqlCeParameter value)
  at SqlCE4Umbraco.SqlCeApplicationBlock.AttachParameters(SqlCeCommand command, SqlCeParameter[] commandParameters)
  at SqlCE4Umbraco.SqlCeApplicationBlock.ExecuteNonQuery(String connectionString, CommandType commandType, String commandText, SqlCeParameter[] commandParameters)

Took a quick look at the source-code. Think it's because there are direct SQL statements being used in "ImageCropPreValue" ... these could be switched over to use the Umbraco core API (in "umbraco.cms.businesslogic.datatype.PreValue/PreValues")?

Thanks, Lee.