Can two metals combine to form a compound?
In short, yes they can. What exactly forms however is quite complicated.
Certain rules have been created to estimate structures but in general it's not as easiy as predicting simple inorganic compounds. 

It's part of a topic that we call intermetallic compounds. Sometimes also called alloys, although this term should not be used. We destinguish four different type of compounds that might arise from two metals. 


Intermetallic Compound: This has a clear stoichiometry (Sodium thallide)
Intermetallic Phase: There is a certain range 
Solid Solution: Two metals can be mixed in all ratios
Alloys: A compound that has more than one of these phases present


Why these compounds form however is often attributed to certain abilities like radii, sometimes electronegativity and something we call valence electron concentration. 

In general we seperate the periodic table into four groups:


Group I + II
Group III - XI
Group XII - XIV (parts)
The rest (if metallic)


Now we can consider each combination of two, either from the same group or from different groups. For example group I + group I will often yield simply a solid solution are both compounds simply mix. Group I + say group XIII however have quite some difference in electronegativity. Here we get stronly polar or perhaps even more like ionic bonds, as compounds like NaTl form. 

In between stuff like Laves-phases can form, compounds that mostly form deltahedra only, or Hume-Rothery-Phases like brass. At some point you get a lot of possible phases and some means to explain why they form and not something else depending on size, electronegativity, valence electron concentration, etc. 

I had a few lectures on these topics and every new lecture would basically introduce a new set of compounds with new rules. You could relate them back to this simple scheme I gave you above but it would always have it's own limitations and set of rules.