Line 4 and Line 5a if Form 8888 are very similar. There is one word that is different.
Line 4 is about all of the bonds that you will be buying for you and your spouse, while line 5a is for you, your spouse, or someone else. Line 4 is the total of the bond purchase and Line 5a and Line 6a shows the individuals who are making bond purchases.
The wording on the form is a unclear.