I’m slightly confused by the question but if I understand it correctly. Your asking about in the finale when they see their S6 selves?

@LR2159 Yes, I'm talking about the finale where they see them S6 selves.

And it’s the same time travel as endgame(quantum realm) so it’s not an alternate timeline unless they took something. Which if I remember correctly, they didn’t

I know but like I don't understand, who it was possible that there were 3 same people at the same time (Jemma from S6, Jemma from S7 and Jemma in space, etc)?

2019 Fitz and Simmons go to space with Enoch to start their plan, their daughter Alya is born. They live to the year 2023 in Theta Sepentis. They then travel back to 2019 when they originally left.

2023 Fitz and Simmons arrive back in 2019 to save the team in the temple, while their 2019 selves are heading to space with Enoch. Fitz and Alya stay in 2019 in the Zephyr pod. 2023 Simmons travels with the team to 1931 and they create an offshoot timeline till 1983.

Using the quantum realm 2023 Fitz travels to the off shoot timeline and retrieves the team to take them back to their original timeline in 2019. While they are in space The 2019 and 2023 versions of Fitz and Simmons and the rest of the 2019 team are running about on Earth. They then all go down to save their original selves to complete the time loop.