Allegations of voting fraud are being investigated by Police Scotland as counting is underway.
Local councils have confirmed possible cases of personation have been reported to police.
Three cases are reportedly being looked into in Glasgow, with one in Renfrewshire Council and another in Stirling.
A Renfrewshire Council spokesman said: "We have been made aware of an incident earlier today in the Paisley and Renfrewshire North constituency where a member of the public arrived at a polling station to place a vote to find that it had already been cast by another member of the public.
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"The matter was reported to Police Scotland and as such is now subject to a police investigation."
Personation is where a person votes in the place of someone else.
BBC Scotland reporter Aileen Clarke said three cases were alleged in Glasgow - in the Central, North and South constituencies.
READ MORE: When will your constituency announce their results?
Another BBC reporter said a ballot paper had been taken away for forensic examination after a voter arrived at a polling station to find someone had voted using their name.
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