Recording Latency/Misalignment of recorded tracks?

I am almost sure that this issue is due to a setting or two. I beleive I am getting confused because there are so many moving parts in this chain.

So here's what i am doing.

I am recording an acoustic guitar over top of several other tracks which includes Bass. Drums, Piano, Strings and a ghost vocal.

I am playng the metronome and drums as I am strumming.

I played an acoustic guitar on two separate tracks. In other words, I recorded the guitar twice.

The funny thing is , when I solo the play back on the two acoustic guitars, they are in time relative to each other. But when I allow all the tracks to play, the two acoustic guitars are suddenly not aligned with the other tracks. When I zoom in and take a closer look, i notice that both acoustic guitars are early. In other words, they both commence a tad bit too soon. When I take each of them and nudge them over to the right slightly, they line up and sound in time with the other tracks.

So the question is:

If I was tracking to the metronome and drums, and if it sounded like I was tracking on time as I was playing, why are both tracks recorded a little early?

I realize that to help me with this, you will need to know a bit about my set up and settings.

I am using an Imac with a Steinberg UR44 sound module.

Under Buffer, I have it set at 64 samples. I also had software monitoring disabled.

I did not have low latency mode selected.

On the Steinberg UR44, I went straight into Input 4. The Steinberg UR44 has the ability to send reverb effects and other effects to the headphones, while sending a dry signal to the DAW. That's how i have it set, so that when laying down a vocal, the singer can hear a wet signal in the headphones, but only the dry signal gets recorded.

So, I'm wondering how the guitars managed to be recorded slightly earlier than all the other tracks. Did I have a setting wrong?

Should I be relying on the Steinberg 44 to send wet signals to my headphones, and could that have messed things up?

As I say, there are so many variables, that it is hard for me to determine what may have caused this.

My goal is to be able to record an inout source ( a microphone for example, or an acoustic guitar etc) , be able to record a dry version of whatever I input, while being able to serve up a wet signal in the phones.

What am i doing wrong?

Thank-you for your time and expertise!