In the first incident in Livingston, West Lothian, a 21-year-old woman was attacked in a back garden in Scott Brae at around 5.20am on Tuesday, April 8.
In a subsequent incident around a month later, a 27-year-old woman was assaulted at an address in Orchard Place in the early hours of Wednesday, May 7.
Detectives said they are keen to speak to a man they believe will be able to help with their inquiries.
He is described as being white, around 5ft 8in to 5ft 10in with dark hair and wearing a grey hooded top.
Information also suggests he has worn a pair of dark-coloured Adidas Adipure Essence trainers.
Police Scotland can be contacted on 101.