Pennsylvania has rejected over 370,000 applications for mail-in ballots, most of which were duplicate requests, according to a report by ProPublica and the Philadelphia Inquirer. The battleground state's election offices rejected 372,000 requests for mail-in ballots, according to the report. About 90 percent of the denied application requests were duplicates, and one out of every five requests have been rejected.
They don't mention the one guy w/ 11 ballots, but The Pittsburgh Post-Gazette (the largest newspaper serving metropolitan Pittsburgh) does: https://archive.is/wip/S2WSS
ProPublica and The Inquirer identified hundreds of voters who submitted three or more duplicate applications; one voter appears to have submitted 11 duplicates.
Here's the left-wing The Hill saying similar: https://archive.is/dV4c7
They don't mention the one guy w/ 11 ballots, but The Pittsburgh Post-Gazette (the largest newspaper serving metropolitan Pittsburgh) does: https://archive.is/wip/S2WSS