Joe was twice accused of, and acknowledged (in a loose sense), plagiarizing; one time what he said, the other what he wrote.
It's hardly as bad as it seems; the first was a one off where he cited in a speech a british member of parliament Neil Kinnock's speech, forgetting that day to note Neil, whereas Joe had indeed credited Neil in six previous incidences of the very speech.
The second was as a freshman in college, claiming he was unfamiliar with the rules for citing sources, quelle surprise, happens regularly to freshman college students. Sophomores too.

Both were members of a left-wing party, waging war against the far-right leaders of their countries, Thatcher and Reagan. And that's why Neil Kinnock, when asked whether he was bothered by the appropriation of his words, responded that he wasn't; to the contrary, he {Kinnock} confessed to feeling 'flattered'. https://psuaw.blogspot.com/

Wiki: {Biden} earned his bachelor's in 1965 from the Univ of Delaware, with a double major in history and political science ... He then entered Syracuse University College of Law,... During his first year there, he was accused of having plagiarized five of 15 pages of a law review article. Biden said it was inadvertent due to his not knowing the proper rules of citation, and he was permitted to retake the course after receiving an "F" grade, which was subsequently dropped from his record.. He received his Juris Doctor in 1968, graduating 76th of 85 in his class. Biden was admitted to the Delaware bar in 1969

May 1989: Senator Joseph R. Biden Jr. was cleared of allegations that he committed plagiarism in law school by a panel under the authority of the Delaware Supreme Court ... The alleged law school plagiarism involved an essay Mr. Biden wrote in 1965 for an introductory class on legal methodology. 'A Personal Vindication'

Proud Pop, Proud Independent, Chief Political Analyst, ABC News; Founder: https://countryover.party , Author, A New Way: Embracing the Paradox.