Problems deleting Activities ?

I usually record my bike rides on both my phone and my watch.  The phone has more accurate GPS data and the watch has the advantage of recording heart rate data.  After a ride I review the data and if the GPS data on the watch looks OK I keep that version of the Activity (and delete the one on the phone to avoid duplication) or if there is a problem with the watch GPS I only keep the phone version.  This has worked quite well for about 2 years (about 400 Activities).  I just noticed that both Activity versions are showing on the Activity listing for the last 4 days, even though I had deleted one of each pair.  As a test, I again deleted a recent duplicated Activity - it disappeared from the Activity page (as expected), but when I refreshed the page it reappeared !  Has someone been tinkering with the design of this part of the web or is there something else going on ?  Maybe it’s a coincidence, but about 4 days ago I recovered an unrelated Activity from the “recently deleted” page.