If you want to stick with a cell-based table view, you can subclass NSCell
and override:
- (void)drawWithFrame:(NSRect)cellFrame inView:(NSView*)controlView
{
NSRect insetRect = NSInsetRect(cellFrame, 2.0, 2.0);
NSBezierPath* path = [NSBezierPath bezierPathWithRoundedRect:insetRect xRadius:3.0 yRadius:3.0];
[path stroke];
[[NSColor whiteColor] setFill];
[path fill];
[[NSColor brownColor] setStroke];
[path stroke];
NSMutableAttributedString* content = [[NSMutableAttributedString alloc] initWithString:@"DUPLICATE"];
NSFontManager* fontManager = [NSFontManager sharedFontManager];
NSFont* font = [fontManager fontWithFamily:@"Verdana"
traits:NSBoldFontMask
weight:0
size:13.0];
NSDictionary* attributes = @{NSFontAttributeName:font,
NSForegroundColorAttributeName:[NSColor brownColor]};
[content setAttributes:attributes range:NSMakeRange(0, [content length])];
[content setAlignment:NSCenterTextAlignment range:NSMakeRange(0, [content length])];
[content drawInRect:cellFrame];
}
The above code generates a cell that vaguely resembles your button (you'll have to tweak fonts, colours, line-styles etc. yourself):

I also adjusted the row height in the table view delegate by providing:
- (CGFloat)tableView:(NSTableView *)tableView heightOfRow:(NSInteger)row
{
return 24.0;
}