Lee Jian Xuan zooms in on similar versions of works by pioneer local artists that have surfaced in galleries and at auctions and asks experts to evaluate their authenticity.

Gibbons by Chen Wen Hsi, ink painting

Both paintings are forged and done by Liu Lang, an acquaintance of Chen's known for forging his works. But Liu signed one painting and signed another as Chen, notes Ms Allison Liu, a Chen collector. She runs Bergen Art Investment, an agency that sources and buys art for high net worth clients.

Ms Janet Fong of Ins' Art International, a gallery specialising in pioneer artists and their second-generation disciples, adds: "You can tell it's Liu Lang's work from the ink strokes. They are painted in a lifeless way, while Chen's strokes are strong and direct. Also, the composition is too similar, suggesting something is off. Chen always varied the composition of his paintings."

Singapore River by Chen Wen Hsi, oil on canvas

The top painting is forged, while the one at the bottom is real, as it corresponds to what was published by Chen in a 1987 book, says Ms Liu.

Ms Fong adds: "Look closely at the paint strokes and the way they are painted. One painting looks like the color was filled in, while the other has layers, variation and texture.

"As a result, one looks three-dimensional and is full of vitality, while the other looks very flat."

Riverside (1976) by Cheong Soo Pieng, oil on canvas

Both Ms Liu and Ms Fong were unable to conclude which of the two paintings is authentic.

"It is unlikely that Cheong created two pieces that are near identical. But all we know is that the one on top comes from a private collection, while the one at the bottom was auctioned at Sotheby's Hong Kong last October for HK$2.08 million (S$359,000)," says Ms Liu.

Ms Fong says: "There are very small, subtle differences. In the auctioned piece, you can see the faces are rounded, while the faces in the other piece are angular and sharp."