Need Help Identifying Chinese Coin

The "design" - round, bronze, square hole in centre, with four characters around it - was used by the Chinese for 2000 years, unchanged except for the characters. Coins of the same design (known in the West as "cash coins") were also used by China's neighbours, most notably Japan, Korea and Vietnam.

This particular coin claims to be from Vietnam. The obverse (bottom pic) names Annamese king Thanh Thai (1889-1907 AD). The reverse (top pic, rotate 90 degrees clockwise) gives the denomination: 30 van (the "van" was the name for a single cash coin in Vietnam).

Unfortunately, Thanh Thai made no 30-van coins; only 1 and 10. That, plus the generally mushy design, tells me this is not an official coin; it was probably made using two different coins to make the moulds; the reverse is taken from the 30-van coins of king Tu Duc.