htaccess files

I am inheriting a site from fellow dev who has different htaccess than I am using to make DA work.

~~

first dev using this

~~~

RewriteEngine on

RewriteOptions inherit

IndexIgnore .htaccess */.??* *~ *# */HEADER* */README* */_vti*

<Limit GET POST>
order deny,allow
deny from all
allow from all
</Limit>
<Limit PUT DELETE>
order deny,allow
deny from all
</Limit>
AuthName www.shorehavenbhi.com
RewriteCond %{HTTPS} off
RewriteCond %{HTTP:X-Forwarded-SSL} !on
RewriteCond %{HTTP_HOST} ^shorehavenbhi\.com$ [OR]
RewriteCond %{HTTP_HOST} ^www\.shorehavenbhi\.com$
RewriteRule ^/?$ "https\:\/\/www\.shorehavenbhi\.com\/" [R=301,L]

# php -- BEGIN cPanel-generated handler, do not edit
# This domain inherits the "PHP" package.
# php -- END cPanel-generated handler, do not edit

~~~

My usual has this which manages SQL input, via webassist.

ErrorDocument 404 /404.html

<IfModule mod_rewrite.c>
RewriteEngine On
RewriteCond %{SERVER_PORT} !^443$
RewriteCond %{REQUEST_URI} !/_mmServerScripts/.*
RewriteRule ^(.*)$ https://%{HTTP_HOST}%{REQUEST_URI} [L,R=301]
</IfModule>

Can they co-exist on server?
What should I change?
Note: I have to keep the older site live while I work on new conversion from GoLive to DW and incorporate mysql / php stuff. There is a significant private area that I will not convert until later, so need to make all of it work ok.

Any help, most appreciated!

We both have our own dedicated servers, but within the same hosting company if that helps.