cloning Beth came during Rick and Morty season 3. Beth was in the middle of a breakup with Jerry and sought adventure, but she put her future in Rick's hands. However, it wasn't until season 4 that Rick and Morty provided any exploration of what happened.
Two versions of Beth were featured in Rick and Morty's season 4 finale, "Star Mort Rickturn of the Jerri." After a full season of Beth reunited with her family, Space Beth arrived as a cosmic warrior who spent her time battling the New Galactic Federation. Space Beth believed that she was a clone after she discovered an implant in her neck, prompting her to return back to Earth to kill Rick. However, she learns that both Beths have such implants, adding to the confusion of who is real and who is a clone. Although both Beths were interested in learning who was real and who was the clone at first, Rick and Morty ended season 4 with the entire family, except Rick, left in the dark. He begins to reveal his "Mind Blower" of the event (a recorded memory), which shows him cloning Beth, but then removing the labels from the cloning vats and rotate their placements repeatedly so he wouldn't know which Beth was real.
Since Rick and Morty didn't provide any answers on which Beth is real and which is a clone, a fanbase built on wild theories has been left to create some more. The truth behind the two versions of Beth is one of the topics that has continued to be debated since season 4 ended, with cases to be made for either Beth being the clone. Since they were exactly the same at the end of the cloning process and Beth's uncertainty about what she wanted, the future for both Beths could just come down to where Rick put them. That said, one of them is definitively a clone, and even if Rick and Morty never answers the question, there's reason to believe that Space Beth is the real, or at least original Beth.
Space Beth's trajectory as a character falls in line with what Beth wanted for herself, based on her discussion about cloning with Rick. She expressed a desire to go have more adventures after spending time in Froopyland with Rick and realizing that she's more like her father than she thought. Space Beth being the real Beth means she finally got the chance to break free of her mundane life and find happiness elsewhere. Although this would mean that the real Beth also abandoned her family, it was already fractured at this time. This arc gives Beth some agency in her story, instead of simply coming to a realization that she was happy all along and just didn't realize it. Plus, it's not like this would be the first time a Sanchez left their family behind to pursue their own interests, so this reveal would further illustrate how similar Beth and Rick are.
Although fans have been quick to point out Space Beth's blue hair strand being similar to Evil Britta's highlight from Dan Harmon's Community, and her being labeled as Clone Beth in the mobile game Pocket Mortys, these could be giant red herrings. The former seems like too big of a clue for Harmon to put in to signify which Beth is a clone, especially considering how Rick and Morty has so far refused to answer the question. Season 5 will continue the storyline and bring Space Beth back, though, so the revelation of who is the real Beth could be right around the corner.