I started my Season 5 rewatch this month in anticipation of BL Season 6 starting in January, and I'm about half way through.  What really struck me was the overall copycat theme and how it permeated the season. There were so many instances of the writers purposefully copycatting - from the ton of parallels to earlier seasons to copycat maneuvers in almost every episode. Liz was copycatting Red's mannerisms throughout. I remember fans on other boards complaining that writers had run out of ideas and were just recycling old ones. But that wasn't the case. They were doing it purposefully and having a lot of fun with it.

5.01  Skinhead drug guys pretend to be U.S. marshals
5.02  The forgery of the Storm on the Sea of Galilee painting. A forger is the ultimate copycat!
5.03  The Miss Rebecca Thrall insurance plot was copycatting the one in Season 1's Milton Bobbit episode.
5.04  Nirah was always pretending to be something she wasn't: a horse breeder, a hotel worker, a nurse.
5.05  Bombings attributed to Illyas Surkov were copycat crimes carried out by Ruther and his task force. And his task force was like the alternate BL task force. The female member of the fake CIA task force strikes some of the very same poses as Ressler and talks about "just doing my job."  Ruther copycats the Red sniper pose from Season 3's Alexander Kirk episode.
5.06  The assassin's wife copycatted the way The Travel Agency carried out its assassinations and the way her husband experienced his Groundhog Day life.
5.07  Dembe pretends to be Malik Charef, an Algerian seeking to be smuggled into Germany.
5.08  Liz returns home to find Tom duct taped in a chair just like he was in the pilot. Garvey knifes Tom the same copycat way Ranko Zamani did in the pilot.
5.09  Liz gives up Agnes in a similar way as Katarina did Liz.  Liz copycats Kaplan in her meticulous cleaning of the cabin and her walk down the road at the end.

Later in the season, we get Liz copycatting the Stewmaker, the copycat killers in The Capricorn Killer, and of course, all the doubling Mr. Raleigh Sinclair does. And it all leads up to Red copycatting the real Raymond Reddington.  And it makes me wonder if a Copy Kat is involved.