Do you have a source on those numbers? I'm not intimately familiar with the topic but 10 million Soviet built AK-47s sounds quite low, the Soviet Union did after all have something like 40 million personnel between it's active military and it's reserves at the point of its collapse (sure not every one of them was a rifleman, but not every single Soviet built AK-47 would have been in their armouries either with military aid to allies and weapons wearing out with use).

China and the Soviet Union were not the only manufacturers of the AK-type assault rifle. Most of the Warsaw Pact nations made their own, as did Yugoslavia, Egypt, North Korea, and other countries.

According to figures given by Theodor Hoffmann, East Germany's last Defense Minister, the NVA (East German army), would have been able to muster a force of about half a million soldiers in case of war in 1990. All of those soldiers would have been equipped with AK-type rifles with, as /u/AlistairStarbuck pointed out, plenty of replacements. In addition to this, many AK-74s (more modern version of the AK platform, firing a different cartridge than the "classic" AK-47/AKM) were made to replace the AKM, but ended up being sold to Iraq and Argentina in order to help keep the DDR financially afloat. I don't know how many weapons were exported, but I would say that, based on the NVA's fighting strength, arms exports (in addition to the AK-74 sell-off, East Germany provided military aid to FARC in Colombia and to the People's Army of Vietnam), and other factors, it would not be unreasonable to say that East Germany alone likely made a million AKs of various types. Naturally, not every man would have been equipped with an assault rifle, but they were issued to non-infantry personnel such as artillerists and such, so a good portion of them would have been armed in this way. This also does not take into account the number of rifles that have been destroyed, but is nevertheless a good starting point.

Now, scale that up to the rest of the Warsaw Pact. Although I don't have comparable figures for the Polish People's Army, Poland's population (37 million) was over twice that of East Germany, so, as mandatory military service existed across the Warsaw Pact, it could likely have mustered twice the military strength and so twice as many AKs. Yugoslavia, in particular, had a reserve force of almost three million people, and an average of four percent of Yugoslavia's overall exports were of military equipment. This totals four million rifles.

The AK platform is relatively simple to produce, and even developing countries often have the means to build a weapons industry around them. Their reliability makes them an obvious choice in conflict zones around the world. If you are interested in reading more about that, I would encourage you to check out http://www.smallarmssurvey.org/ .