Does Google Play continue to serve older APKs when the latest APK is already at 100% for a week or more?

I'm currently looking at over a few thousand new installs each day for an older version right now and the referrer source seems to be from google/facebook.

I know of two possible scenarios:

1. Installs from third party stores/hosting sites
2. An older active apk with a lower minimum sdk version being served to users no longer eligible for latest version

The second point doesn't apply and the referral source negates the first so I'm wondering if it's possible for Play Store to keep serving an older version. Is anyone else also seeing installs for older versions even now?