Horseshoe Theory
The idea that extreme opposites on a spectrum sometimes loop back around and appear to be very similar.
Examples
In politics, the far-left and far-right fringes of a society might be equally violent and seemingly want the same things. They might both want to bring down the government, believing it to be corrupt for opposite reasons.
George Lincoln Rockwell was a white supremacist and the founder of the American Nazi Party. His Wikipedia page states:
As a supporter of racial segregation, he agreed with and quoted many leaders of the Black nationalism movement such as Elijah Muhammad and early Malcolm X.
The YouTube video When Wokes and Racists Actually Agree on Everything is a comedy sketch demonstrating how the two sides of racial debate might agree.
An installment of the Saturday Night Live recurring sketch Black Jeopardy! includes a middle-aged Donald Trump supporter (played by Tom Hanks) who surprisingly turns out to be in agreement with the Black contestants.