RW pump/new impeller bolt question

Can't figure this out...

I ordered new RW impellers for my 8v71TIs through Amazon - showed up in two days with free shipping, WOW! But on to the question...

THe Jabsco impellers came with a gasket and 6 bolts for the pump cover. 4 of the bolts are SS, two are bronze. Howscome? Why would there be any advantage to a mix of the bolts and where would you put the two bronze bolts? THis is not a big issue for me, I don't use the "new" bolts anyway but can't understand why they would supply the fasteners that way.

Am I missing some obvious scientific thing here?

My guess is that the 'Nobel Prize Winner' that packaged it at the fulfillment center is responsible. Probably attracted by the contrasting pretty colors of the screws...or am I two crewed...

P.s., my original screws are in brass from what I can see.

P.s. 2: Are they all the same thread and of what material were your originals?

Ahhh... Jabsco pumps are a wonderful thing arent they? Kinda reminiscent of model T stuff; FOOLPROOF. Ive had SS and bronze, slotted screws and cap screws all mixed together with ZERO results. Especially with all the bonding going on with these boats, I see no problems. FWIW... the screws are
1/4-20s
I agree with SB, the college grad with the masters degree likes the color contrast ... I say mix them every other one so that Dr. Brainiac doesnt get disappointed. (!) Dont forget the center plug to keep the spline from corroding, and use some never sieze too. ws

Just flipped my color combination bolts out to all SS this season.