To reproduce
- add Calculator column in the grid
- set the EnterKeyMode to EnterMovesToNextRow
- press enter when the cell is in edit mode.

Workaround:

-use custom GridDataRowBehavior like this:

class MyNewEnterBehavior : GridDataRowBehavior
{
    bool firstTime = true;
    protected override bool ProcessEnterKey(KeyEventArgs keys)
    {
        if (this.GridControl.IsInEditMode && this.GridControl.CurrentColumn is GridViewCalculatorColumn )
        {

            if (firstTime)
            {
                firstTime = false;
                return false;
            }
            firstTime = true;
            return base.ProcessEnterKey(keys); 
        }
        return base.ProcessEnterKey(keys);
    } 
}