M. Buliga, version: 24.06.2019
The duplication of \x.((\y.yy)(xx)), an example proposed by ishanpm, computed with (hapax). The chemistry is "chemlambda-var", which has diferent A-FO and A-FOE rewrites, and without the FO-FOE rewrite.
Alternatively you can see the same reduction with the js version of chemlambda (here).