A police spokesperson say the two houses were targeted between the evening of Friday 19 October and the morning of Sunday 20 October 2024.
The damage caused consists of a smashed car windscreen, broken wing mirror, stolen number plate, and human excrement being smeared onto a wall.
Guernsey Police said the investigating officer would be particularly keen to speak to anyone who has private CCTV or Ring doorbells in the area.
“If you have any information regarding this incident you are asked to contact PC 94 Dan Hopkins on 222 222 or to contact Crimestoppers anonymously on 0800 555 111,” said the police spokesman.