A pic would help. but unless you plan on staining the board darker, most likely not. It is most likely a mineral stain which can range from just very dark to black, maybe a worm stain, (bluishish to purple, ambrosia) , fungus (spalting) or just some heartwood. more amber to brown. Let's see a pic and go from there? if heartwood you MAY ??? be able to bleach it, but that is questionable as well. ( i've never seen it match quite right)
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