Fixed generating an error when calling 'select data for fitting' twice.
Fixed generating an error when calling 'select data for fitting' twice.

SasView/sasview,lewisodriscoll/sasview,lewisodriscoll/sasview,lewisodriscoll/sasview,lewisodriscoll/sasview,SasView/sasview,SasView/sasview,SasView/sasview,lewisodriscoll/sasview,SasView/sasview,SasView/sasview