These two references are actually used in very different ways in these two stories. In "Clay," the tracts that are hung up on the walls in the laundry where Maria works are something she does not like because they offend her Catholicism, as the laundry is owned and ran by Protestants:
There was one thing she didn't like and that was the tracts on the walls; but the matron was such a nice person to deal with, so genteel.
The tracts then become a symbol of Protestantism and the way in which this religion offends Maria's religious sensibilities.
In "Eveline," however, the picture of the priest represents the yellowing, stagnant life that she herself is experiencing, and that she is hoping to escape from. Note how this is referenced:
Perhaps she would never see again those familiar objects from which she had never dreamed of being divided. And yet during all those years she had never found out the name of the priest whose yellowing photograph hung on the wall above the broken harmonium beside the coloured print of the promises made to Blessed Margaret Mary Alacoque.
Here, the photograph of the anonymous priest, who managed to escape to Melbourne, as her father tells her, stands as a taunting symbol of elusive freedom but also the stagnation and paralysis that of Eveline's own life. It is important to note that this photograph is the first of the "familiar objects" that is mentioned. The reader is meant to infer that this priest who managed to emmigrate has held a particular fascination for Eveline. It both simultaneously symbolises the hope of freedom but also the particular paralysis associated with remaining in Dublin. Of course, at the end of the story, Eveline's position is defined more by the photograph than by the actual priest; she is unable to flee and is left with these "familiar objects" to become discoloured and gradually fade over the years. Both objects then are used in very different ways in these two stories.