What does the IR of a compound with multiple carbonyl groups look like?

Question: What does the IR of a compound with multiple carbonyl groups look like?

Answer: Each carbonyl in theory should have its own distinctive stretch around 1700 cm^-1, but as you might expect sometimes the carbonyl peaks might overlap with each other.

Here is a quick case study using IR spectra from SDBS:

methyl acetoacetate - ketone vs. ester. Notice how you can distinguish the two peaks at 1748 cm^-1 vs 1718 cm^-1 and they both appear as "knubs" on a large peak

2,3-hexanedione - ketone vs ketone, but these ketones are NOT fully the same... not sure what is going on and why there are three/four peaks clustered (1770, 1717, 1689, and maybe 1644?)