equal straight 5 realizations
ACCEPTED Realization 1
Type Polysemy
Language Classical Arabic
Lexeme تَعَدَّلَ taʕaddala
Meaning 1 it became, or was rendered, straight, or even
Direction
Meaning 2 to be equal taʕaddalat ḳīmat-u l-matāʕ-i bi-kad̲ʕ
the value of the commodity was equal to such a thing
Reference Lane: 1973
Comment

V stem from عَدَلَ meaning 1) to be fair, righteous, just; 2) to decline, deviate. 

ACCEPTED Realization 2
Type Polysemy
Language Croatian
Lexeme ravan
Meaning 1 equal ravan geniju, ravan nuli
equal to genius, equal to zero
Direction
Meaning 2 straight
Reference HJP
Comment
ACCEPTED Realization 3
Type Internal cognates
Language Russian
Lexeme 1 равный
Lexeme 2 ровный
Meaning 1 equal
Direction
Meaning 2 straight
Reference <personally collected data>
Comment
ACCEPTED Realization 4
Type Polysemy
Language Serbian
Lexeme раван (ravan)
Meaning 1 equal бити раван оцу (с оцем) по храбрости
to be equal to his father in courage
Direction
Meaning 2 straight у равној линији
in a straight line
Reference Vujanitsh et al. 2007: 1100
Comment
NEW Realization 5
Type Polysemy
Language Tamil
Lexeme cemmai
Meaning 1 equality
Direction
Meaning 2 straightness
Reference Fabricius Tamil: 437
Comment

It seems that this binary polysemy pattern is a part of different larger pattern, in comparison with other realizations of this shift: 

other meanings of this lexeme are: 1) excellence, dignity 2) redness, orange or gold colour.