I have had several problems recently, where data was lost or replaced by errant data in a particular form. Two things have happened: data already entered vanished for a particular record. In another instance, data for a particular record was replaced with data from some other record. Then, I noticed that there were two open windows with the same name. One had altered up the data for the record (showing different data than was correct in one, but not other of the two windows with the same name). this is highly concerning with regard to data integrity. Similar untrackable problems in the last three weeks.
It’s certainly possible to purposefully have multiple windows with the same name – for example by opening clone windows or using the windowtitle statement. Probably you would have mentioned if you had used one of these techniques, so I’ll assume you haven’t.
If a form encountered an Objective-C error that prevented the opening process from completing you might be able to open a form more than once with the View menu. In that case I wouldn’t expect the form window to work at all. There were bugs of this type in the early years of the Panorama beta, but I haven’t seen a bug like that in at least 3 or 4 years.
There was a bug in the b19 release that could cause different windows to show different data for the same record, much like you are describing. It turned out that the display was wrong, not the data, so there was no actual database corruption. But I assume that you are not using the b19 release, which was “recalled” over 3 months ago. There have been no further reports of this problem since b20 was released in late August.