DMARC Check failed for receiving mail

I have a fortimail appliance which says DMARC Check failed because of 2 DKIM signatures for same domain.

One is valid the other is invalid but fortimail decides to say that DMARC is invalid because of this.

Is this a expected behaviour?

DMARC: DKIM header aligned, DKIM signature invalid d=example.com headerFrom=example.com
DMARC: DKIM header aligned, DKIM signature valid d=example.com headerFrom=example.com