This is a good question, and I wish I had a more specific answer. I am not the first educator to try to find the answer to your question, and it has become clear to me after an hour of researching that, while there are real people in the world with the last name Morcerf, there is not a particular meaning attached to the name.
Here is what I did find for you. Alexandre Dumas was a prolific writer of fiction. While he did work with several collaborators and even assistants who helped him outline his ideas before writing, he has more than a thousand known works attributed directly to him. That is a prodigious amount of writing over a period of about forty years, and of course he had to have a strategy for his stories, settings, and characters. According to the Britannica Encyclopedia, linked below, this was how Dumas worked.
Dumas does not penetrate deeply into the psychology of his characters; he is content to identify them by characteristic tags (the lean acerbity of Athos, the spunk of D'Artagnan) and hurl them into a thicket of wild and improbable adventures where, after heroic efforts, they will at last succumb to noble and romantic deaths. His heroes and heroines, strong-willed and courageous beings with sonorous names, are carried along in the rapid movement of the dramas, in the flow of adventure and suspenseful plots. Dumas adhered to no literary theory, except to write as the spirit moved him, which it did often.
This excerpt makes it clear that Dumas simply wrote what pleased him. While he did write about some historical or literary figures, such as the Musketeers, he usually just wrote characters he liked into whatever situations he could think of for them.
The connection to your question comes in this phrase: "His heroes and heroines, strong-willed and courageous beings with sonorous names." Sonorous means having a pleasant sound, and that is, it seems, how he chose the name Morcerf. It is pronounced mohr-SEHRF, and there is something distinctly and beautifully French as well as something suggestive of trouble in this name. The prefix "mor-" or "mors-" means death, thus the words morbid, mordant, mortuary...you get the idea. These two things, it seems to me, are rather in keeping with the character of Albert de Morcerf. He is a fine person, but he does have his moments.
Perhaps there is more to this name, but my searching did not reveal it.