@JediShark - I kinda doubt it, based upon our membership audience of retirees. Let me catch you up to what I've done since talking with Cristian...
I cloned the production site over to a dev sub-domain and tried to replicate the problem but could not do so (I may have mentioned that bit already). A day or so after that though, I had an idea based upon performance problems I was having with my personal website that uses the same hosting provider. One of their suggestions was to upgrade its version of PHP from v5.6 to 7.2 and add some memory usage parameters to the php.ini file.
So it hit me that when I created the new sub-domain for testing/troubleshooting this problem on our club's membership site, it was created with the latest version of PHP. So I checked the version on our prod site and sure enough, it was still on v5.6 also. So I upgraded it to v7.2 on Feb. 16th, I believe. Since then we've had no double-payments but we haven't really had a lot of renewals or new sign-ups:
- 1 on the 16th
- 3 on the 17th
- 1 on the 18th
- 14 on the 19th (nite of our meeting)
- 1 on the 20th
- 2 on the 21st
So I still have my fingers crossed!!
We've got house guests thru Sunday though, so my time is limited until next week. Sorta wish I could say that I could have reproduced the problem on the dev test site but...
thanks for following up.