It’s getting hard to draw distinctions between Presidents Biden and Trump. The news over the weekend is that the investigation into President Biden’s classified documents is heating up rather than powering down. It blurs the supposed distinctions between Mr. Biden and his predecessor. The president’s personal attorney reports that a Friday search of Mr. Biden’s Wilmington home turned up six more documents.

The president struck a defiant tone before the latest search, insisting  to reporters on Thursday that “We’re fully cooperating” and that he has “no regrets.” He twice repeated that “there’s no ‘there’ there.” These latest discoveries come after a drip-drip of disclosures that have turned up classified materials at the Penn Biden Center at Washington and at his Wilmington garage, where the box of documents was kept adjacent to a vintage Corvette. 

Senator Manchin, the fence-sitting Democrat of West Virginia, is taking a cautious approach, telling CNN’s Fareed Zakaria, “Let’s wait and see. Some people are taking sides. ‘OK, it was more egregious than what President Trump did or what President Biden did.’ And maybe that’s true. I don’t know. Maybe it’s not true. Let’s find out.” Leading that effort will be a special counsel, Robert Hur. 

The image of a renegade President Trump squirreling secrets — and what he calls “cool” but empty  folders — away at his Florida manse now is incomplete without a matching tableau that includes a two month gap between when Mr. Biden’s lawyers discovered the documents and the acknowledgment of that cache to the public. The president’s lawyers insist that they are cooperating with authorities, but so does Mr. Trump. 

For his part, Mr. Trump sees in Mr. Biden’s travails a doppelganger of his own. The former president asked,  “When is the FBI going to raid the many homes of Joe Biden, perhaps even the White House?” The contrast between the search warrant that swung open the gates of Mar-a-Lago and what the FBI called the  “planned, consensual” search of Mr. Biden’s residences no doubt rankles Mr. Trump and his supporters.

Mr. Trump’s recalcitrance in respect of turning over documents has been well observed, but Mr. Biden’s mixed pattern of compliance, alternatively executed by his own lawyers and DOJ officials, and only belatedly related to the public, suggests clumsiness if not criminality. The documents predate his time at the Oval Office, meaning he cannot retrospectively avail himself of the presidency’s awesome powers. There is only one chief executive at a time. 

Our own editorial to “hold the Justice Department to a single standard” in investigating the two presidents relied not merely on a similar fact pattern, but on an underlying instinct for fairness. As stashing documents increasingly appears to be not breach peculiar to Mr. Trump but a practice he shares with his successor, the notion of handing up an indictment on one but not the other loses logic. Presidents live not only in a white house, but a glass one, too.