As a general rule all approaches to SIN are radar vectors to the ILS so the chance of lining up on the most Easterly r/w are, I would say, nil. If the crew elect to go visual and line up on the wrong r/w radar will soon tell them and the crew should be monitoring the ILS anyway, (SOP).
SIA do a fair amount of training out of Changi and it is just a possibility that the RSAF might let them use their r/w for touch and goes to keep the training a/c away from commercial traffic.
Otherswise I'd say it never happened.