The Aprilia Racing rider took his 19th career win in the seventh round of the FIM Superbike World Championship, storming to a 5.5-second win over Briton Jonathan Rea (Honda).
Biaggi had earlier stormed from 10th on the grid to win race one, with the double victory increasing his Championship advantage over Rea from 18 to 38.5 points.
Another Brit, Leon Haslan of BMW Motorrad Motorsport, completed the podium four tenths behind Rea.
Tom Sykes, who started the day on pole, finished a disappointing seventh.
Seven riders failed to finish the race, including Carlos Checa, who crashed on lap four after a risky move from Marco Melandri, who was exonerated after an investigation and finished fourth.
Race 2 results:
1. Max Biaggi ITA Aprilia Racing RSV-4 39m 01.869s
2. Jonathan Rea GBR Honda WSBK CBR1000RR +5.355s
3. Leon Haslam GBR BMW Motorrad S1000RR +5.731s
4. Marco Melandri ITA BMW Motorrad S1000RR +7.004s
5. Ayrton Badovini ITA BMW Italia Goldbet S1000RR +7.921s
6. Michel Fabrizio ITA BMW Italia Goldbet S1000RR +17.291s
7. Tom Sykes GBR Kawasaki Racing ZX-10R +17.351s
8. Loris Baz FRA Kawasaki Racing ZX-10R +17.630s
9. Jakub Smrz CZE Liberty Effenbert Ducati 1098R +18.211s
10. Matteo Baiocco ITA Barni Ducati 1098R +28.131s
11. Maxime Berger FRA Effenbert Liberty Ducati 1098R +28.407s
12. Hiroshi Aoyama JPN Honda WSBK CBR1000RR +38.060s
13. Niccolo Canepa ITA Red Devils Ducati 1098R +49.003s
14. John Hopkins USA Crescent Fixi Suzuki GSX-R1000 +51.881s
15. Leon Camier GBR Crescent Fixi Suzuki GSX-R1000 +55.502s
16. Leandro Mercado ARG Pedercini Kawasaki ZX-10R +1m 06.361s
17. Federico Sandi ITA Grillini Progea BMW S1000RR +1m 29.918s
18. Eugene Laverty IRL Aprilia Racing RSV-4 19 laps completed
19. Chaz Davies GBR ParkinGO MTC Aprilia RSV-4 15 laps completed
20. David Salom ESP Pedercini Kawasaki ZX-10R 7 laps completed
21. Davide Giugliano ITA Althea Ducati 1098R 5 laps completed
22. Carlos Checa ESP Althea Ducati 1098R 3 laps completed
23. Lorenzo Zanetti ITA PATA Ducati 1098R 2 laps completed
24. Sylvain Guintoli FRA Effenbert Liberty Ducati 1098R 1 lap completed