The fines, issued on October 11 and 16, were handed out in Star Road after reports of gatherings involving more than 30 people.
Officers attended both incidents, which were reported by members of the public.
The occupants from the two different households – a 34-year-old woman and a man, 37 – were issued with the fines in line with Covid-19 legislation.
Tougher measures targeting the most serious breaches of social distancing restrictions came into force in August, in the hope of placing a new deterrent on the breaches that put the public most at risk.
Those facilitating or organising illegal raves, unlicensed music events, or any other unlawful gathering of more than 30 people face a £10,000 fine.
Fines of £100 can continue to be issued to those who participate in illegal gatherings and those who have already received a fine will see the amount doubled for each new offence, up to a maximum of £3,200.
Detective Superintendent Andy Gipp said: "When it comes to the Covid-19 regulations, enforcement is still the last resort.
"However, the law and the message on the rule of six, and hosting large gatherings, has been clear.
"People cannot expect to gather in large groups, for example at house parties, without there being positive enforcement action. This means large fines.
"We all have our own part to play, and a level of personal responsibility, in stopping the spread of the virus.
"The police and the local community must continue to do all that is reasonable, and possible, to halt the rise in Coronavirus cases and support the local health services."
Acting Police and Crime Commissioner, Ray Bisby, added: "As the number of Covid-19 cases continue to rise nationally, preventing the spread of Coronavirus continues an effort we all have a personal responsibility to support.
"Whilst the majority of people across Cambridgeshire and Peterborough have adhered to government guidance, I want to take this opportunity to reassure people that where there are breaches of the rules on gatherings, officers will continue to apply the same approach as they have done throughout this crisis.
"That approach is to engage, explain and encourage people to follow the new regulations before using enforcement as a final tactic.
"I am pleased to see officers working hard to positively patrol public spaces and proactively engaging with communities where there have been challenges around compliance.
"Those who continue to put others at risk will be challenged."