As I understand it, a Christmas Eve Mass will not fulfill our Sunday obligation for the 4th Sunday in Advent. So if we attend Mass Sunday morning and then a Christmas Eve Mass in the evening, can we receive the Eucharist at both Masses? Thanks!
Yes. Ordinarily, you can receive Communion twice in one day so long as the second reception takes place within the context of attending Mass. If you meet the separate obligations for the Fourth Sunday of Advent and for Christmas by attending two Masses on December 24, you can receive Communion at both Masses.