You need to use 1 deny line:
Order allow,deny
Allow from all
Deny from 12.34.56.78 12.34.56.79 12.35.67.98
I'm not 100% sure, but I think the order you specify allow and deny in the "Order" line needs to be mimicked in the subsequent lines. For example:
Order [color=green]allow[/color], [color=red]deny[/color]
[color=green]Allow[/color] from all
[color=red]Deny[/color] from 123.234.245.250
or
Order [color=red]deny[/color], [color=green]allow[/color]
[color=red]Deny[/color] from all
[color=green]Allow[/color] from 192.168.1.1