Valvira says it received an anonymous tip that this second person's diploma from a Russian medical school may also be bogus, as Laiho's is believed to be.
Valvira had issued the individual with a six-month permit to work as a doctor in Finland.
The agency says it will check the diplomas of all Russian-trained doctors it has licensed to work in Finland over the past 20 years.
Valvira estimates that this will involve dozens of people, perhaps more than 100. Medical Counsellor Pirjo Pennanen of Valvira told YLE that a more precise figure will be available on Thursday.
She says that Valvira is focusing on Russian medical schools simply because the two suspected cases that have emerged now are related to Russia.
Pennanen adds that the Supervisory Authority is tracking where the second suspected pseudo-physician has worked. However she does not believe that this person has treated a large number of patients.