Grace cannot be quantified so getting “double the grace” doesn’t make sence.
The Code of Canon Law for the Latin Church allows for the reception of Holy Eucharist twice in a day only if the reception in both instances is within a Mass in which one is an active participant. You may not receive at what Latin Church parishes call a “Communion Service”, when the reserved Sacrament is administered, and also receive in a Mass.
The readings used in the Mass have no effect. You may receive in two Masses in one day with the same readings, or in two Masses with different readings-- one Latin ordinary readings, one Latin parish patronal feast day readings, one Dominican feast readings, or Eastern Catholic or one funeral, or some other reason for readings that may be other than the ordinary ones for that day. That has no relevance.