Model Aircraft Monthly ran a two part article, Feb March 2007, on Soviet Catalinas. The USSR started licence production before the war. These were for civil use. I doubt if the US Government would have allowed Consolidated to help them build military versions. During the war they received later versions of the Catalina under lend lease.
The search Catalina was a PBY-1 that American scientists had been preparing for an expedition to New Guinea. At the time it was the only civil version of the Catalina in the US. It was called Guba but has been confused with another Catalina named Cuba. They wanted it becuase it had the most advanced instruments, radio and additional fuel tanks. Dr. Archbold, the owner, was reluctant to sell it but great pressure was put on him to do so. The US Navy lifted the embargo on exporting PBY-1s to allow Archbold to receive a replacement out of turn. He was also given a $20,000 discount. During the search Guba was flown by Canadian pilots. (Since the DB-A was likely to have crashed on the northern coast of Alaska or Canada the search was lauchned from that side of the ocean.)It then returned to the US because the US Navy insisted that it could not be delivered to the USSR before 1st November 1937. In December it went back to Consolidated for minor repairs and upgrades. Finally in June 1938 it arrived, unassembled, in sixteen boxes at the Leningrad port Grebnoy.
Guba was lost in late July 1942 of the south-western coast of Novaya Zemlya. U-601 surfaced unexpectedly in the bay and opened fire on two flying boats moored there. Guba was set on fire and sank drowning one of the flight mechanics. The pilot, Kozlov, swam 1,640 feet to the shore in ice cold water.
The lasted edition of Model Aircraft Montly, Jan 2008, has an article on Soviet B-25s.