The pair, aged 34 and 36, lost their jobs after admitting gross misconduct and being found guilty of a breach of integrity by police chiefs.
The constables were dismissed without notice after the misconduct hearing on Thursday.
They were not named by the Metropolitan Police.
Downing Street police officer PC James Addison, 37, was dismissed in June after sharing extreme pornography on his phone while on duty.
He sent other officers "disgusting and offensive" images that included bizarre sex acts and scenes showing defecation.
The images were found on his phone during the investigation into the so called "Plebgate" affair, in which former government chief whip Andrew Mitchell MP was accused of calling officers plebs during an argument at the gates of Downing Street - an allegation he has denied.
No further action was taken against PC Addison over that matter.
PC Addison, from Rayleigh in Essex, admitted sharing the images and was suspended from duty in December 2013.
In May, at Westminster Magistrates' Court, he was sentenced to a Â£6,000 fine, Â£120 victim surcharge and forfeiture of his mobile phone after he admitted 11 counts of publishing an obscene article.
A total of 14 officers were investigated for either criminal offences or misconduct after the porn was found.
No more criminal action will be taken and the matter has been concluded, the Met said.
Det Ch Supt Alaric Bonthron said: ''The sharing of these images is completely unacceptable."
Two police officers from Scotland Yard's Diplomatic Protection unit have been sacked for sending obscene images from their mobile phones.