Can "(thou) beest", and "(thou) art" be used interchangeably?

Update: The form "beest" certainly appears many times in the classic literature... I'm assuming from Taivos' answer it's an uncouth manner of speech, can someone confirm that?
Update 2: Julius Caesar by Shakespeare, William If thou beest not immortal, look he Merchant of Venice by Shakespeare, William If thou beest rated by thy estimation, Tempest by Shakespeare, William If thou beest Stephano, touch me, and Tess of the d'Urbervilles - A Pure Woman by Hardy, Thomas Ah,... show more Julius Caesar by Shakespeare, William
If thou beest not immortal, look


he Merchant of Venice by Shakespeare, William
If thou beest rated by thy estimation,


Tempest by Shakespeare, William
If thou beest Stephano, touch me, and


Tess of the d'Urbervilles - A Pure Woman by Hardy, Thomas
Ah, th'st think th' beest everybody, dostn't, because th' beest first favourite with He just now


As You Like It by Shakespeare, William
Within these ten days if that thou beest found


Ivanhoe by Scott, Sir Walter


Paradise Lost by Milton, John
If thou beest he; But O how fall'n


All's Well that End's Well by Shakespeare, William
[To DIANA] If thou beest yet a fresh uncropped flower,


King Henry V by Shakespeare, William
thou beest mine, Kate, as I have a saving faith within me tells
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