Thinking logically, (or maybe I'm not), one shallott planted last year yields, say, 6 bulbs. These go on this year to grow 6 each. That's 36 bulbs that could be sitting there from the one bulb last year.
If that is the case, for them all to bolt, there should be 36 flower stems where each bulb was originally planted. I assume this is not the case.
I would have a closer look, there may be some useable, albeit small bulbs because of the overcrowding.
Wouldn't comtemplate eating the flower stems.
Please note the emphasis on the "could, if & may", no promises, no guarantees.