Floating Static Routes - phantom entries

Scarborough

Hi, have a (physical) multi-user lab setup with Cisco 1921 & 2921 routers connected to a core switch + Cisco 2921.

Have recently seen floating static entries appear on 2 of the 20 edge routers - remote network 192.168.1.0 /24 (far side of Core Router), AD 254. At 1st I assumed that these had been entered manually, but am not convinced now.

Are there any circumstances under which this can happen, if we discount deliberate / accidental manual entry ??

Thanks in advance.