Try...
B3:E8:
<TABLE style="WIDTH: 192pt; BORDER-COLLAPSE: collapse" border=0 cellSpacing=0 cellPadding=0 width=256><COLGROUP><COL style="WIDTH: 48pt" span=4 width=64><TBODY><TR style="HEIGHT: 15pt" height=20><TD style="BORDER-BOTTOM: windowtext 0.5pt solid; BORDER-LEFT: windowtext 0.5pt solid; BACKGROUND-COLOR: transparent; WIDTH: 48pt; HEIGHT: 15pt; BORDER-TOP: windowtext 0.5pt solid; BORDER-RIGHT: windowtext 0.5pt solid" class=xl65 height=20 width=64>X</TD><TD style="BORDER-BOTTOM: windowtext 0.5pt solid; BORDER-LEFT: windowtext; BACKGROUND-COLOR: transparent; WIDTH: 48pt; BORDER-TOP: windowtext 0.5pt solid; BORDER-RIGHT: windowtext 0.5pt solid" class=xl65 width=64></TD><TD style="BORDER-BOTTOM: windowtext 0.5pt solid; BORDER-LEFT: windowtext; BACKGROUND-COLOR: transparent; WIDTH: 48pt; BORDER-TOP: windowtext 0.5pt solid; BORDER-RIGHT: windowtext 0.5pt solid" class=xl65 width=64 align=right>3</TD><TD style="BORDER-BOTTOM: windowtext 0.5pt solid; BORDER-LEFT: windowtext; BACKGROUND-COLOR: transparent; 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BORDER-TOP: windowtext; BORDER-RIGHT: windowtext 0.5pt solid" class=xl65></TD></TR></TBODY></TABLE>
D3, confirmed with CONTROL+SHIFT+ENTER:
=LOOKUP(MAX(COUNTIF(B3:B8,B3:B8)),{0,3,4,5,6},{0,3,4,5,""})
E3, confirmed with CONTROL+SHIFT+ENTER:
=IF(D3<>"",INDEX(B3:B8,MATCH(D3,COUNTIF(B3:B8,B3:B8),0)),"")
Note that if there are two values that each occur three times, the formula returns the first occurrence.