Two terminally ill patients died on the day they were given the wrong medication at a care home in Tenterden, a medical misconduct hearing was told.
Barbara Gambier, 64, and Mary Quinn, 61, were in charge of the Acacia House care home when blunders affecting up to 12 residents were made.
Bungling staff administered the wrong doses of morphine, mixed up patients' rescriptions and failed to fill in charts correctly between July 2004 and May 2005 - all on the pair's watch - the Nursing and Midwifery Council (NMC) hearing was told.
David Christie, for the NMC, told the hearing that Mrs Gambier, the manager, should have been aware of the practices, which he described as 'well known and ongoing' and put a stop to them.
And her deputy Mrs Quinn is alleged to have directly witnessed a number of instances of malpractice in administering drugs.
Mr Christie pointed to three separate incidents where residents had been given each others' prescription drugs.
He said on May 17, 2005, a terminally ill man - Patient E - was given a 20mg dose of Oramorph, an orally administered form of morphine, when he had only been prescribed 10mg.
The panel heard the drug had come from stock intended for Patient D, also critically unwell, and that medical notes incorrectly stated he had been given Diamorphine - a different drug.
Patient D's chart was also filled in with the wrong dose on May 15, 2005.
Both patients died on the days that the mistakes were made, but Mr Christie stressed Mrs Gambier and Mrs Quinn were not to blame. But he added: "The council would say that that was a significant issue in the light of the fact that Patient D sadly passed away that day."
The panel heard that a similar error was made over a period of several days in August and September 2004, when medication intended for one patient was given to another.
Mr Christie said: "This is the third example of medicines being borrowed among patients. Management, and particularly Mrs Gambier would, the council submit, have a responsibility to ensure that this practice does not occur.
"It's relevant that a total of six nurses were involved in either administering or witnessing these particular dosages. This, the council says, supports the contention that this was a well-known, ongoing practice within the home and the manager should have known that."
The allegations came to light after Elsie Coke, regional manager of Charing Healthcare, which owned Acacia House, investigated the home's logbooks.
Mr Christie said: "Acacia House was, at the time of these matters, a 41-bed residential home.
"It came to Mrs Coke's attention that there were some discrepancies in the home's medical records. She investigated matters and discovered a number of issues with the residents in that particular home."
Mrs Gambier, from Rolvenden, is accused of failing to ensure that her staff administered, recorded the administration and disposed of medication in an appropriate manner between July 2004 and May 2005.
She has since resigned from the home in Ashford Road, St Michael's, Tenderden.
Mrs Quinn, of Coxheath, near Maidstone, is accused of witnessing a resident being given morphine which had been prescribed for a different patient; failing to ensure that another patient's dose of morphine was reduced as requested; filling in a medication chart incorrectly and administering the wrong dose of morphine to a patient.
She also faces a charge relating to the illegal destruction of medication at the home on three occasions.
If the charges against the pair are proved, they could be struck off the nursing register.
The hearing continues.
The current owners of Acacia House, 1st Choice Care Homes, have asked to point out that they purchased the home during 2007 and had no connection to the home at the time of the incidents which are the subject of the misconduct hearings.