The first 16-year-old victim noticed him sitting on a bench seat outside the changing rooms before she entered the cubicle.
It was after she had undressed, standing in her underwear, she noticed the defendant under the changing room wall looking at her. She panicked, got dressed and left the changing rooms.
About 15 minutes later, the second victim, also 16, and her friend entered the area.
"While victim two was trying on clothes with her friend, she felt someone's hand rubbing her leg.
Victim two and her friend got dressed, left the changing room cubicle and sat on the seat.
The second victim saw someone crawling underneath the cubicles and then Collier walked out of the end cubicle and sat beside the second victim's friend.
"He told victim two and her friend that he would not leave until they left," the statement says.
Collier left the shop when a shop assistant asked him to.
In an explanation to police, Collier said the indecent assault was not a charge.
On February 11, Collier entered the Kelvin Hotel via a fire exit and made his way to the seventh floor where he entered a room.
"This room was occupied by a 12-year-old female guest whose parents were at the hotel function room," the summary states.
The girl was startled and ran off to find her parents.
When questioned by staff, Collier said he was a government agent and was looking for the manager.
Collier, who received his second strike warning at an earlier court appearance, was already on the Child Sex Offender register. Judge Swaran Singh said Collier had received his first strike warning in 2017 after he was convicted of assault with intent to commit sexual connection.
Defence counsel John Fraser said the indecent assault was not at such a level as if he had been in the same room as the victim.
However, the judge said the victims were in a confined area which put them at greater risk than if they had been in a more public place.
Taking into account the impact statement of one of the victims, Judge Singh sentenced Collier to 26 months' imprisonment.
