Contradiction with Exodus 12:29
This verse reinforces the event by stating it actually happened, not providing a contradiction.
Exodus 12:29: And it came to pass, that at midnight the LORD smote all the firstborn in the land of Egypt, from the firstborn of Pharaoh that sat on his throne unto the firstborn of the captive that [was] in the dungeon; and all the firstborn of cattle. [dungeon: Heb. house of the pit]
Contradiction with Numbers 33:4
Similar to Psalms 78:51, it recounts the same event, hence it doesn't offer a contradiction.
Numbers 33:4: For the Egyptians buried all [their] firstborn, which the LORD had smitten among them: upon their gods also the LORD executed judgments.
Paradox #1
The contradiction in that verse could potentially relate to the concept of a widespread, divine action affecting the firstborn of a nation. From a scientific standpoint, such an event would require explanation through natural, biological, or historical processes, which are not accounted for in modern science. The description of a supernatural occurrence affecting many individuals simultaneously does not align with contemporary scientific understanding of biological phenomena.
Paradox #2
The moral conflict in Psalms 78:51 could be the portrayal of God causing suffering to innocent children as a punishment for the actions of others. This can raise questions about justice and fairness, as it seems to contradict the idea of a compassionate and loving deity.