fix: multifield join should produce the same set of outputs
fix: multifield join should produce the same set of outputs

sgiavasis/nipype,FCP-INDI/nipype,sgiavasis/nipype,sgiavasis/nipype,dgellis90/nipype,mick-d/nipype,FCP-INDI/nipype,pearsonlab/nipype,pearsonlab/nipype,mick-d/nipype,FCP-INDI/nipype,iglpdc/nipype,mick-d/nipype,iglpdc/nipype,carolFrohlich/nipype,iglpdc/nipype,iglpdc/nipype,mick-d/nipype,carolFrohlich/nipype,dgellis90/nipype,sgiavasis/nipype,FCP-INDI/nipype,pearsonlab/nipype,carolFrohlich/nipype,dgellis90/nipype,dgellis90/nipype,pearsonlab/nipype,carolFrohlich/nipype