According to Collins Dictionary “double-faced” means ‘deceitful’.
Can both adjectives of the Title box be used interchangeably in the sense of deceit?
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Example: Trains were double headed for most of the day with every possible combination of locomotive.
Example: a double-headed axe. (Lexico)
Double-faced or two-faced (adj): 2. Tending to say one thing and do another; deceitful.
Example: were you double-faced—did you betray them?’
You cannot interchange 'double-headed' and 'double-faced' to mean 'deceitful'. They have different meanings.
You can use 'duplicitous' or 'two-faced' instead of 'double-faced'.
Duplicitous (adj): deceitful. (Lexico)
Two-faced (adj): Insincere and deceitful. (Lexico)