Multiple Comparison Statement in Bash Fails - Bash: [: Missing `]'

The correct syntax of if for expresions in bash are this refrence:

Table 7-2. Combining expressions

Operation                  Effect
------------------    ------------------
[ ! EXPR ]            True if EXPR is false.
[ ( EXPR ) ]          Returns the value of EXPR. This may be used to override the normal precedence of operators.
[ EXPR1 -a EXPR2 ]    True if both EXPR1 and EXPR2 are true.
[ EXPR1 -o EXPR2 ]    True if either EXPR1 or EXPR2 is true.

your if statement should be like this:

if [ "$SECONDS" -ne "$one" -o "$SECONDS" -ne "$two" ]

You can also use [[ keyword:

if [[ "$SECONDS" -ne "$one" || "$SECONDS" -ne "$two" ]];

Here is it's chart help [[:

 EXPR1 && EXPR2   True if both EXPR1 and EXPR2 are true; else false
 EXPR1 || EXPR2   True if either EXPR1 or EXPR2 is true; else false

When you start your statement using [ then space and another [; Bash will think that you are running a test (First [) on an other test (second [).

And before your || it will look for a ]literal, can't find it and complains about it.