McCann, 33, is known to use false names, most recently Joel.
The victims were snatched separately, with the first taken from a street in Chingford at around 12.30am on Thursday.
The second was taken at around 12.15pm in Edgware that day.
They were driven to a hotel in Watford where an attempt was made to book a room for around 1pm.
The suspect then left the premises after a room was unavailable.
A struggle then took place between the women and suspect at around 2.30pm in Osborne Road, Watford, before the women managed to escape.
“McCann is considered extremely dangerous and a risk to the public and we ask people not to approach him, but instead call 999”
Cops are trying to trace a silver or grey-coloured Ford S-Max people carrier – which had false registration plates – in connection with the offences.
Detective Chief Inspector Katherine Goodwin, from the Met Police, said: “We would ask anyone with any information about McCann’s whereabouts to contact us immediately – McCann is considered extremely dangerous and a risk to the public and we ask people not to approach him, but instead call 999.
“If you wish to remain anonymous, call Crimestoppers. It is vitally important we trace him in connection with these offences.
“My team continues to work around the clock and we are making progress in furthering the investigation.”
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