Inconsistent warnings when combining eras with different labels/names about era HOT 1 CLOSED

library("era")
yr(1, "BP") + yr(1, "cal BP")
#> Warning: eras have different label or name parameters.
#> # BP years <yr[1]>:
#> [1] 2
#> # Era: Before Present (BP): Gregorian years (365.2425 days), counted backwards from 1950
c(yr(1, "BP"), yr(1, "cal BP"))
#> Warning: eras have different label or name parameters.
#> # BP years <yr[2]>:
#> [1] 1 1
#> # Era: Before Present (BP): Gregorian years (365.2425 days), counted backwards from 1950