(as) (a)like as (two) peas in a pod
Said of two people who are very similar in interests, actions, or appearance. Betty and Jennifer are as alike as two peas in a pod, so it's no wonder people sometimes mistake them for sisters.
like as two peas in a pod
Very similar, bearing a close resemblance. For example, They're not even sisters, but they're like as two peas in a pod. This expression alludes to the seeds contained in a pea pod, which do indeed look very much alike. [Late 1500s]