To add to my colleague's response, please note that parties cannot take inconsistent factual positions in court due to the doctrine of judicial estoppel, and you may be able to exploit inconsistencies as may be appropriate.
I'll also add 2 comments: at least a couple of things are terribly wrong in terms of wasting time and judicial resources when there are 2 separate lawsuits between the same parties, and one of them files a motion for summary judgment but then withdraws it before the hearing.
PLEASE READ THIS BEFORE YOU COMMENT, EMAIL ME OR PHONE ME. I'm only licensed in CA. This answer doesn't make me your lawyer, and neither do follow-up comments and/or emails and/or phone calls, and you shouldn't expect me to respond to your further questions if you haven't hired me. We need an actual agreement confirmed in writing before any attorney-client relationship is formed. This answer doesn't constitute legal advice, and shouldn't be relied on, since each state has different laws, each situation is fact specific, and it is impossible to evaluate a legal problem without a comprehensive consultation and review of all the facts and documents at issue.
I think that you are suggesting that there was documentary evidence or an affidavit from either plaintiff or some witness that was submitted to the court as part of plaintiff's motion for summary judgment, If that is the case, you may use such documents in a different case as proof of the plaintiff's admission as to any particular state of facts.
The withdrawal of the motion only gets rid of the motion; it does not undo what was said.
Good luck to you.
Michael S. Haber is a New York attorney. As such, his responses to posted inquiries, such as the one above, are limited to his understanding of law in the jurisdiction in which he practices and not to any other jurisdiction. In addition, no response to any posted inquiry should be deemed to constitute legal advice, nor to constitute the existence of an attorney/client or other contractual or fiduciary relationship, inasmuch as rendering legal advice involves the ability of the attorney to ask appropriate questions of the person seeking such advice and to thus gather appropriate information. In addition, an attorney/client relationship is formed only by specific agreement. The purpose of this answer is to provide the questioner with general information, not to outline specific legal rights and remedies.