10 point discrepancy between two batches with exactly the same grain bill?

intended to do a head to head comparison between s-05 and 1056, so i brewed two PM worts with the same grain bill and DME's, the first came out extactly where i expected at 1050, the second somehow is measuring at 1060. So what gives, i realize that many things could have potentially been different between the two mashes, but since i strived to maintain the same temps and other mash conditions constant, what could possibly explain such wildly discrpant strengths?

I mashed 4 lbs. of grain for both recipes

Possibilities but none seem sufficient: mash temp diff's (seems minimally likely)
mash thickness (could only have been a few cups different in terms of water volume)
same water
same sparge technique and volume

So the only thing that i can think of is that somehow an extra pound of DME got into my batch without me knowing it, which seems unlikely!

and yes the temps of both wort samples taken for gravity readings were at 60 deg. (and even if they were 20 deg. different that couldn't explain a 10 point swing anyhow)

So i leave it to the experts to conjecture this one, thanks!

The most common problem in SG doing PM and extract batches is insufficient stirring before taking the gravity reading. Give it another good swishing and try again.

The brewing Gods are dickin with you...

Mash temps and thicknesses shouldn't affect original readings...but will affect final gravity.

Your BMC swilling neighbor probably popped in when you weren't looking and added a lb or so of sugar.


Otherwise, what fingers said.