It is mostly likely from another satellite with a similar orbital track as METOP-A but at a lower frequency.
On another note, would you be willing to extend your antenna’s UHF frequency to 400-470 MHz? It’s currently set to 430-470 Mhz. That would open up the possibility observations at your station for a bunch of satellites in the 400 - 402 MHz range.
More info this thread for more info.
satcolintel5