What date was the second Easter?

Question

When did the early Christians celebrate the second Easter? Did it fall on the same day as the Jewish Pasch (Sabbath day / Saturday) or on the next day (Sunday)?

Answer 1

OP: When did the early Christians celebrate the second Easter? Did it fall on the same day as the Jewish Pasch (Sabbath day / Saturday) or on the next day (Sunday)?

In common across the Christian world, for roughly 100 years after Christ's instatement of the Christian Passover observance, it was held on whatever day of the week the 14th-16th Nisan fell. It was like Christmas held on the 25th on whatever day of the week it fell.

According to Irenaeus, the change from the observed "whatever day" to a fixed "Sunday" began with Pope Sixtus of Rome.

For the controversy is not merely as regards the day, but also as regards the form itself of the fast. ... And this variety among the observers [of the fasts] had not its origin in our time, but long before in that of our predecessors, some of whom probably, being not very accurate in their observance of it, handed down to posterity the custom as it had, through simplicity or private fancy, been [introduced among them]. ... And the presbyters preceding Soter in the government of the Church which thou dost now rule—I mean, Anicetus and Pius, Hyginus and Telesphorus, and Sixtus—did neither themselves observe it [after that fashion], nor permit those with them to do so. Fragments III Irenaeus

To be clear, the "fixed Sunday" is not traceable to apostolic teaching.

This variety of observances lasted until Nicea. At Nicea, the decision was finalized to observe Sunday, rather than the actual day with Constantine as the guarantee. They determined to observe the first Sunday after the Spring Equinox after the first full moon (15th of Nisan) in remembrance. See here for determining Easter date.

our worship follows a more legitimate and more convenient course (the order of the days of the week) ... it has appeared good to all; and I [Constantine] have been guarantee for your consent, that you would accept it with joy, as it is followed at Rome, in Africa, in all Italy, Egypt, Spain, Gaul, Britain, Libya, in all Achaia, and in the dioceses of Asia, of Pontus, and Cilicia. from Constantine's letter

So, to answer the OP, the second Passover following the first one instituted by Christ would have been observed on whatever day of the week 14th-16th Nisan fell. This common observance lasted about 100 years until Sixtus introduced the fixed day and about 200 years later the fixed Sunday was enforced.

Answer 2

What date was the second Easter?

I guess some would postulate that the second Easter or Resurrection was that of Mary, the Mother of Jesus.

According to some traditions, Mary died on the 13th of August and was assumed into heaven (resurrected from the dead) on August 15th. Some traditions placed the year of Mary’s death in 41 A.D., 43 A.D. or 48 A.D. The most common one being August 15, 48 A.D. This would be the second Easter in the Early Church.

Almost halfway between Easter and the end of the liturgical year, it is a “little Easter,” reminding us that Jesus’ Resurrection was not just a one-time event but the start of a process intended to enfold the whole of humanity. Easter begins what ends in the “resurrection of the body” on the Last Day — and which the Assumption already shows us is intended to include humanity. Yes, the Assumption is a personal honor to Mary, the woman who bore the Son of God in her body. But, if Jesus’ rising from the dead is the “first fruits” (1 Corinthians 15:20) of redemption, Mary’s Assumption is “second fruits” — and pointing to the fullness of the harvest on the Last Day. - Jesus’ Resurrection, Mary’s Assumption and Our Glorious Resurrection on the Last Day

Answer 3

The first Jewish Christians would have celebrated the Passover and the Feast of Unleavened Bread as they always had. They may have singled out the 14th of Nisan as well for special Christian rites, since that was the day of the crucifixion (at least as the Gospel of John has it); or they may have singled out the Sunday that fell within the week of Unleavened Bread for special esteem, since Sunday was a Christian festival in any case. The extent to which such practices spread to Gentile Christians is not clear, but Paul writes to his Gentile converts expecting them to know when Pentecost is (1 Cor. 16.8. See also the mention of Yom Kippur in Acts 27.9). Clearer evidence for an annual Easter emerges in the late 2nd century, as another commentator has already noted.