How to capture, if at all, proxy merge information?

[matentzn]

Frequently, we get situations like

O1:A -[exactMatch] -> O2:X
O1:A -[exactMatch] -> O2:Y

i.e. where one term in a source terminology (O1) is equivalent to two terms in a target terminology (O2). This happens when a curator in O1 determines that O2:X and O2:Y are actually the same thing and only erroneously exist as separate identifiers. There exist many such examples in Mondo for example.

Is it useful to capture this explicitly as part of the metadata? Saying something like subject_id_proxy_merge: true? I am a bit on the fence here as I think this information is:

1. useful to see in the table for curators on the one side
2. redundant with the information communicated by the table (i.e. you can just see O1:A maps to two terms, and get the same information).

I am tending to not include this property, but I wanted to see whether there are any other opinions.