Seems that minecraft allows you to add same generator element more than once.
I tried this... use one of presets, lets say use tunneler's dream. Add ,lake,lake,lake,lake,lake at end. It will either generate very slowly or run out of memory. I tried 5 mineshifts, but ran out of memory. 😛
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It's the same bug in the sense they are both bad user input. In any case, this is no longer a problem in the latest snapshot using the options you used.

<sarcasm>Then let's mark all bugs that cause crashes as duplicates of each other: "It's the same bug in the sense they both cause minecraft to crash".</sarcasm>

It should be linked with "relates to" rather than "duplicates".
How is this duplicate of MC-1510 ?? It's completely different bug!