Can You Ovulate Multiple Times in One Cycle?
No -- once you ovulate, rising progesterone prevents a second ovulation from happening that cycle. Some women do get a second LH surge (which can trigger a positive OPK), but that surge doesn't lead to a second release of an egg.
Ovulating twice in the same cycle is a persistent myth in the TTC community. The evidence says you simply cannot ovulate multiple times in one cycle.
Not the same as releasing two eggs
To be clear, this isn't about releasing two eggs at once -- fraternal twins are all the proof you need that this happens. The myth is about ovulating on one day, then ovulating again days later.
Where the myth comes from
It seems to trace back to both the TTC community and, oddly, the scientific community itself. A 2003 paper reported a second (or even third) LH surge after ovulation, alongside what looked like a second ovulation event. Theoretically this shouldn't be possible: progesterone rises after ovulation specifically to prevent a second one. And unsurprisingly, other scientists later identified significant methodological flaws in that 2003 study -- no one has been able to reliably reproduce a genuine second ovulation since, despite real attempts.
From the TTC community's side, some women do report getting a positive OPK again a week or so after ovulation -- and that's real; a second LH surge does happen for some. But that surge doesn't trigger another ovulation. The American Pregnancy Organization sums it up well: "A woman should not ovulate more than once during each cycle. This is due to a careful balance of hormones and their levels -- it takes just the right timing and release of hormones to bring on the release of a mature egg."
References
Baerwald, Adams & Pierson (2003). Fertility and Sterility, 80(1), 116–122. McDonough (2004). Fertility and Sterility, 81(3), 729–730.
Common questions
What about fraternal twins -- doesn't that prove you can ovulate twice?
No -- fraternal twins come from releasing two eggs at the same ovulation event, not from ovulating on two separate days weeks apart. Those are different things.
Why do some women get a positive OPK again a week after ovulation?
Some women do get a second LH surge later in the cycle, but the evidence shows it doesn't lead to another ovulation -- progesterone from the first ovulation prevents it.