As a general rule, we must not draw conclusions from any one witness regarding a matter. The LORD says that on account of two or three witnesses a matter shall be established:

A single witness shall not rise up against a man on account of any iniquity or any sin which he has committed; on the evidence of two or three witnesses a matter shall be confirmed. - Deuteronomy 19:15

The word "multiply" (rāḇâ in Hebrew) is defined as: "be or become great, be or become many, be or become much, be or become numerous"

God blessed them; and God said to them, 'Be fruitful and multiply, and fill the earth, and subdue it; and rule over the fish of the sea and over the birds of the sky and over every living thing that moves on the earth.' - Genesis 1:28

In the verse prior, the same word is used to command kings of Israel not to multiply horses:

Moreover, he shall not multiply horses for himself, nor shall he cause the people to return to Egypt to multiply horses, since the LORD has said to you, 'You shall never again return that way.' - Deuteronomy 17:16

• Does this mean that a king can only have one horse? Certainly not.

Verse 17 also says, with the same word, that a king should not multiply silver and gold.

• Does this mean that a king can only have one coin? Certainly not.

God told us that He gave King David his master's wives (2 Sam 12:8)

I also gave you your master's house and your master's wives into your care, and I gave you the house of Israel and Judah; and if that had been too little, I would have added to you many more things like these! - 2 Samuel 12:8

and said that He would have given him more. God does not participate in sin (violation of His law) and God does not tempt us into sin. King David already had multiple wives prior to God giving him Saul's wives.

• Does God contradict Himself? No.
• God is not the author of confusion (1 Cor 14:33).
• God does not tempt us into sin (James 1:13).

Conclusion

This law cannot be interpreted to mean that a king of Israel can only have one wife without taking it out of context, and applying it in an illogical manner. If one is being logically and exegetically consistent they would also have to limit a king to one horse, one gold, and one silver.

Taking that notion further, they would also have to limit Christian men to one wife, one horse, one gold, and one silver if attempting to use this verse to say that a man can only have one wife as a Christian.