Could be. This is not an entirely new story. I noted the fragment as possibly mentioning Hezekiah's name (badly damaged, of course) back in 2009. See here and here. I don't think I knew about the other fragment, discovered by Shiloh in 1978.
The fragments are tantalizingly ambiguous and may or may not belong to the same inscription. The angel Lacunael has been at work here.
It does look plausible that we are dealing with one or two monumental lapidary inscriptions. Those were expensive to produce. It seems likely they came from some official, possibly royal, source. But it is difficult to say more unless we find more fragments.
For more on the Hezekiah bulla, see here and links. For more on the Siloam Tunnel Inscription, see here and many links.
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