Two men have taken goods and cash worth a total £9,000 from shops in Linton and Sutton.
The men, armed with crowbars, entered the Co-op on Linton's High Street at around 7.15pm on February 24 and forced their way into the tills and the safe.
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Shop staff stood back for safety while CCTV caught the suspects in the act.
Two days beforehand, on February 22, two men entered the One Stop on High Street in Sutton, near Ely.
They arrived at around 8.45pm and were wearing balaclavas and were armed with crowbars.
Cash and cigarettes were taken from the tills worth around £1,000.
Detective Constable Henry Longhurst, of Cambridgeshire Constabulary, said that officers believe the incidents are linked.
DC Longhurst said: "These incidents were both terrifying for the staff involved.
"We believe these robberies to be linked and would like to hear from anyone who recognises these incidents or witnessed them, to get in touch."
Reports can be made to officers online (https://www.cambs.police.uk/) or by phone on 101.
Witnesses can quote reference 35/12993/22 for the incident in Sutton and 35/13490/22 for the incident in Linton.
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