This is a pictograph of an adult person holding a tally stick in each hand. It is an ideograph for the verb to double-check.
Illustrative Text Reference:
Harappa: Tablet incised: H-951 A: Sayid Ghulam Mustafa Shah and Asko Parpola, 1991: Corpus of Indus Seals and Inscriptions: Volume 2: Page 341: Collections in Pakistan: Suomalainen Tiedeakatemia.
Comment:
There is only one extant example of this Indus sign.
Image Credit:
Indus Script Sign Number 24: Sign List of the Indus Script: Iravatham Mahadevan, 1977: The Indus Script: Texts, Concordance and Tables: The Director General Archaeological Survey of India.