CommSec's historical data is more accurate if you are wanting to compare historical prices relative to PSY's capital structure prior to today's placement because CommSec's historical data is an adjusted price that accounts for the renounceable rights issue (dilutive capital raising) that occurred in Aug, 2013. Although the actual high price did print at $4.05 (26 July, 2006), the Yahoo Finance data (on the chart you linked to) has not adjusted for the Aug, 2013 rights issue.
Some people perform analyses in which they want the actual price traded, regardless of subsequent capital events. For those types of analyses the Yahoo Finance data would be what they would look at.
PSY Price at posting:
52.5¢ Sentiment: None Disclosure: Not Held
