Regards to CloudFront certificates, does AWS detect if we re-use a cert from the Load Balancer?
I believe AWS does not detect if we re-use the same cert from LB.
For CloudFront distribution, if you intend to use a Custom SSL certificate, the certificate has to be requested/imported into ACM in US-East-1 region (N.Virginia). You can choose the existing certificate for CloudFront and LB.
Please refer to the links below