Copying Text without incrementing

Trying to use a double-click to copy (replicate) data down the column.
ie.

Column A Column B
ABC OPDOP 507200.55.01
DEF OPDOP 507200.55.01
GHI OPDOP 507200.55.01

However, data in column B is incrementing the ... 55.01
... 55.02
...55.03

How can I get around this without forcing a 'OPDOP 507.55.01' quotes around it of formulas. My users are not sophisticated and I want to minimize their data entry. Thanks, Karen

=A1 would return ABC I want to return whatever the last OPDOP 507200. whatever.whatever. I typed. I may be filling in 1 or 2 or as many as 50 cells down column B with this data. I wanted to keep away from Copy;Paste and Copy;Paste Special Values. Anyother suggestions?