Detective Ash Clements of the Adult Sexual Assault Team said there was a concerning pattern of behaviour exhibited in the alleged offending against the two victims.
The women were at the retreat at different times and were not known to each other.
"We are seeking anyone who has previously visited the Maraehako Bay Retreat, worked in any capacity at the retreat, or from members of the community who may have information that is relevant to the investigation to make contact with our team," Clements said.
"We would like to hear from anyone who may have had similar experiences at the retreat to come forward to police.
"We can assure any other victims who would like to contact us that they will be treated with respect and we will do everything we can to support them."
The alleged offender will next appear in court on December 19.
Information can be provided to the Whakatane Police Adult Sexual Assault Team on (07) 308 5255, or anonymously via Crimestoppers on 0800 555 111.