If you think the 2003 "45th Anniversary of Sino-Cambodian Diplomatic Ties" issue having 2 different commemorative first day postmarks is a record (see hyperlink at the end), you have to see the 1999 China'99 Stamp Expo issue.
A sheetlet containing 8 stamps plus a label was issued in 1999 to celebrate the China'99 Stamp Expo. The official side product is a set of 2 FDC with a printed pagoda cachet which echoes the pictorial theme of the stamps - pagodas of Beijing.
The standard first day postmark depicts the Beijing Tienning Temple pagoda, and the stylized pagoda image is identical to that of the FDC cachet.
Most collectors think that is all. Much to everyone's surprise, 8 more different first day postmarks depicting the 8 pagodas shown on the stamp set were silently available at the expo venue:
This makes Tianning Temple Pagoda have 2 different postmarks featuring it.
The stamps and postmarks are the work of COPREFIL of Cuba. The company also prepared a set of 8 postcards for this issue but not officially available in Cambodia.
Below shows China'99 stamps used on cover to Canada:
Please click here to read "45th Anniv of Sino-Cambodian Diplomatic Ties (II)".
(Special acknowledgement goes to Mr Wu Gang)