Here is what the Java API doc has to say about currentTimeMillis():

Note that while the unit of time of the return value is a millisecond, the granularity of the value depends on the underlying operating system and may be larger. For example, many operating systems measure time in units of tens of milliseconds.

I think the problem is in com.icesoft.faces.component.outputchart.ChartResource#calculateDigest. It is using System.currentTimeMillis() to try to generate a unique number. The resource registry must be using this number to generate the resource name. The problem is that System.currentTimeMillis() can potentially generate duplicate numbers if the machine system time doesn't have enough granularity. Need to find another way to generate a unique number.

With the exact same war file, the problem occurs on Arran's machine but not mine. We have the same versions of JDK and Tomcat. The only thing different is the OS. Strange!

Can't reproduce problem, no matter how many times I reload the page or press the reset button. See screenshot-1.

Please try to reproduce this issue, Arran claims he can consistently, if necessary go see Arran.