Couple of things to consider. Are these "estimates" or hard bids? The word "estimate" is often mistakenly thought to be the same as a bid, it is not. An estimate by definition is an approximate cost arrived at for purposes of bidding a job or reviewing a bid. Normally a contractor performs an "estimate" for their own use, and submits a "bid" to you.
If these are bids, are they based on detailed drawings and specifications you put together? If not, what is the basis upon which the "estimate" was arrived at? The two contractors could be bidding totally different scopes of work, different quality and quantity of fixtures and finish.
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