The term is coined (we think) by psychologist Dan Gilbert. It's a phenomenon that's all too common in creative environments. There are noteworthy examples of plagiarism among prominent professionals that are generally attributed to an accident or oversight.
Well-respected figures from historian Doris Kearns Goodwin to economist and CNN analyst Fareed Zakaria to then-Senator Joe Biden cribbing part of a speech from the Irish prime minister have all acknowledged acts of plagiarism in their own work.
Perhaps most famously, George Harrison was sued in the 1970s over his hit song "My Sweet Lord" by the creators of an earlier rock-and-roll hit, "He's So Fine" – and lost, big-time. Harrison eventually admitted that he hadn't consciously copied the original song, but that he had done it.
Studies of brainstorming groups done by psychologists back up the prevalence of kleptomnesia, especially in workplaces where constant multi-tasking is all too common. Their suggested solution to the condition: cut back on workplace distractions – especially multi-tasking. Good luck on that front.