index/match formula for duplicate values not working

Attached has thirty one dummy part numbers and delivery dates in Part Number order in sheet1.

Sheet 2 needs the list in Date order, updated automatically when new entries are made on the Part Number sheet.

Achieved that with array formula in Col B: {=SMALL('Part Order'!B:B,1)},{=SMALL('Part Order'!B:B,2)}, etc.

Problem is that some dates have multiple parts, but Index/Match duplicates the first Part Number for that date.

Thought following formula would do it by adding row numbers, but it generates blanks:

{=IFERROR(INDEX('Part Order'!A1:A31,SMALL(IF('Part Order'!B1:B31=B2,ROW('Part Order'!B1:B31)-ROW($E$1)+1),ROWS('Part Order'!A1:A31))),"")

Any solutions, suggestions or alternatives welcome as ever.

Ochimus