Bug in Graph Definitions?

[Hathor27]

I defined a graph out of several sensors, as

bug_original.PNG (11.22 KiB) Viewed 7704 times

If I save this graph, exit graph defintions and edit this graph
again, it shows as

bug_after.PNG (11.34 KiB) Viewed 7704 times

What happened? Sensor t1 mutated to t10

Boris, could you please check this?

[Hathor27]

Has anyone else seen such a curiosity too? - It only occurs with more than 5 graphs in a chart